research questions for testing on animals

100 Questions to Ask About Animal Testing

Exploring the topic of animal testing can stir up a complex web of questions that balance scientific inquiry, ethical considerations, and compassionate concern. As a society increasingly focused on the welfare of all living creatures, examining the multifaceted aspects of animal testing is essential.

This article delves into critical questions that reveal the ethical dilemmas, scientific necessities, and regulatory frameworks that underpin the practice of animal testing. By interrogating these concerns and fostering a dialogue around them, we can better understand and shape the future of research and animal welfare.

Table of Contents

Ethical Considerations of Animal Testing

• What ethical principles are at stake in animal testing?
• How is the welfare of the test subjects taken into account?
• Is there a moral justification for using animals in research?
• Are animals used in tests sentient and capable of feeling pain?
• What are the ethical differences between using animals for medical vs. cosmetic testing?
• How do researchers address the issue of consent with regard to animal testing?
• Are the rights of animals considered when developing testing protocols?
• Is the suffering caused to animals during testing proportional to the potential benefits?
• What ethical training do personnel involved in animal testing receive?
• How do ethical review boards oversee animal testing practices?
• Are the five freedoms of animal welfare maintained in laboratories?
• What ethical alternatives to animal testing are being developed?
• How is the public made aware of the ethical implications of animal testing?
• Do government regulations adequately protect animals from unnecessary suffering?
• What role do ethics play in the decision to end an animal’s participation in a test?
• How is the necessity of each test weighed against ethical concerns?
• Is there transparency regarding the ethical dilemmas faced in animal testing?
• How are animals humanely euthanized following test procedures?
• Are there ethical guidelines for the care of animals bred for testing?
• Can consumer choices influence the ethical landscape of animal testing?

Scientific Validation and Necessity

• What are the scientific justifications for the use of animal testing?
• How do researchers ensure the results from animal testing are applicable to humans?
• What efforts are made to minimize the number of animals used in testing?
• How accurate are animal models in predicting human responses?
• What steps are taken to prevent duplication of tests on animals?
• Are there cases where animal testing has been proven unnecessary retrospectively?
• How has animal testing contributed to major medical advances?
• What measures are in place to ensure the humane treatment of animals during experiments?
• How is the refinement of animal testing techniques advancing science?
• Are there specific diseases or conditions for which animal testing is still essential?
• What scientific criteria determine when an animal must be used in testing?
• How often are test protocols revised for scientific validity?
• What advancements are being made in alternative in-vitro testing methods?
• How do peer-reviewed studies influence the practices of animal testing?
• What role does public funding play in determining which tests are performed on animals?
• How often do scientists reassess the relevance of animal testing models?
• Are there industry-wide standards for the scientific procedures involving animals?
• What is the role of genetic modification in animal testing?
• How do international scientific communities view animal testing?
• What is being done to improve the quality of life for animals used in research?

Regulatory and Legal Framework

• What laws govern animal testing practices?
• How do these regulations vary by country?
• What legal protections are in place for animals used in testing?
• Who is responsible for enforcing animal testing laws?
• What are the penalties for violating animal testing regulations?
• How often are facilities that use animal testing inspected?
• Are there legal requirements for transparency in animal testing data?
• How are whistleblowers protected in the context of animal testing?
• What is the process for approving new animal testing methods?
• Are there legal mandates for seeking alternative testing methods before using animals?
• How do trade agreements impact animal testing regulations?
• What legal resources are available for advocacy against animal testing?
• How are regulations adapted in response to scientific advancements?
• Is there a legal framework for international cooperation in regulating animal testing?
• What are the limitations of current animal protection laws?
• How does the law address the use of endangered species in testing?
• Are there legal provisions for the ethical treatment of laboratory animals?
• What role do governmental organizations play in overseeing animal testing?
• How have legal actions influenced the practices of animal testing?
• Are there incentives for companies to follow best practices in animal testing?

Animal Welfare Concerns

• How do testing facilities ensure the physical health of animals in their care?
• What systems are in place to monitor the psychological well-being of animals?
• How are pain and distress managed and minimized during testing?
• What types of enrichment are provided to animals in laboratory settings?
• Are there standards that define adequate housing and care for lab animals?
• How are animals selected for testing, and what happens to them afterward?
• What measures are in place to treat animals humanely during testing procedures?
• How do animal welfare organizations impact the treatment of animals in testing?
• What veterinary care is provided to animals undergoing testing?
• What contingencies are in place for unexpected illness or injury during an experiment?
• What are the survival rates for animals after they have been used in testing?
• How is animal suffering assessed and documented by researchers?
• Are there specific species that are protected from use in testing?
• What are the long-term effects on animals that have undergone testing?
• How transparent is the reporting of animal welfare concerns in testing?
• Are animal welfare audits conducted by independent bodies or internal staff?
• How can individuals report concerns about animal welfare in testing facilities?
• What training does staff undergo regarding animal handling and welfare?
• How often are animal welfare policies reviewed and updated?
• Is there a system for adopting animals out after testing is complete?

Support for Cruelty-Free Alternatives

• What are some leading cruelty-free alternatives to animal testing?
• How can consumers identify products that have not been tested on animals?
• What roles do governments and NGOs play in promoting cruelty-free alternatives?
• How much research funding is allocated to developing non-animal testing methods?
• Are there certifications for companies that commit to cruelty-free practices?
• What technological innovations are driving the move toward alternative testing?
• How effective are cruelty-free alternatives compared to traditional animal testing?
• What incentives are there for companies to switch to cruelty-free testing?
• How do consumer buying habits impact the demand for animal testing?
• What educational resources are available to learn about cruelty-free products?
• How are industry partnerships furthering the development of alternatives to animal testing?
• Is there a cost difference for companies using cruelty-free methods versus animal testing?
• What economic impact does choosing cruelty-free options have?
• Are there global efforts to share knowledge on cruelty-free research methods?
• How is the progress in cruelty-free alternatives communicated to the public?
• What role does consumer advocacy play in supporting cruelty-free products?
• Are there case studies of companies that have successfully transitioned to cruelty-free methods?
• What challenges do companies face when implementing cruelty-free testing?
• How are regulations adapting to support and validate cruelty-free methods?
• What are some success stories where cruelty-free alternatives have replaced animal testing?

Frequently Asked Questions

How can i find out if a company conducts animal testing.

Information about a company’s testing practices is often available on their website, through their customer service, or via their corporate social responsibility reports. Additionally, several organizations provide lists of companies that do or do not test on animals.

How can scientists and researchers be held accountable for adhering to animal welfare standards?

Accountability comes from strict enforcement of regulations, peer review processes, mandatory ethical review committees, transparency in publishing research results, and input from external welfare audits.

What is the role of education in shaping the future of animal testing?

Education plays a crucial role in informing future scientists, policymakers, and the public about the ethical, scientific, and welfare issues associated with animal testing, potentially leading to more humane and innovative scientific practices.

Final Thoughts

Dialoguing about animal testing is not a simple matter of scientific debate—it’s probing into the heart of ethics, empathy, and innovation.

With these questions, readers are equipped to critically assess the imperatives and the impacts of animal testing. The answers to these questions have the power to drive change, endorse progress in scientific practices, reduce harm, and honor our moral responsibility towards the animals with whom we share our world.

As we reflect on these inquiries, let’s also recognize our collective ability to influence and advocate for a more humane approach to research and development.

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120 Questions to Ask About Animal Testing

Animal testing is a controversial issue that has led to many scientific and medical advancements. To understand its impact, we must ask the right questions and look beyond surface-level knowledge.

By exploring topics such as animal welfare, scientific necessity, and ethical considerations, we can engage in a more informed and thoughtful dialogue.

Table of Contents

About Ethics

About science and accuracy, about laws and regulations, about company policies, about animal welfare, about alternatives, frequently asked questions, final thoughts.

• Is animal testing morally right?
• Are there other ways to test products without using animals?
• Do animals feel pain during testing?
• Is it fair to risk an animal’s life for human benefit?
• How similar are animals to humans in terms of biology?
• Do the benefits of animal testing outweigh the harm done to animals?
• Are animals given good living conditions during testing?
• Is animal testing necessary for medical advancements?
• Can computer models replace animal testing?
• Is it ethical to use animals for cosmetic testing?
• Are animals in testing labs treated with respect?
• Who oversees the treatment of animals in labs?
• Is there a difference between testing on different types of animals?
• What laws exist to protect animals used in testing?
• Do some countries have stricter regulations on animal testing than others?
• Are there alternatives that are less harmful but as effective?
• Should there be limitations on the types of tests performed on animals?
• Are the test results from animals reliable for understanding human effects?
• Do animals have rights, and are those rights violated during testing?
• What ethical guidelines do scientists follow in animal testing?
• How accurate are animal testing results in predicting human outcomes?
• What is the rate of false positives or negatives in animal testing?
• Are some animals more reliable than others for certain types of testing?
• How do researchers make sure the tests are as accurate as possible?
• Are there standard protocols for ensuring consistency in animal testing?
• How often are animal tests peer-reviewed for scientific accuracy?
• Do scientists cross-reference animal tests with alternative methods to verify results?
• How do inaccurate test results impact the ethical concerns about animal testing?
• What steps are taken when a test on animals doesn’t provide clear or usable data?
• How are the health and genetic history of test animals controlled to ensure accurate results?
• Are there types of testing where animals have been proven to be especially inaccurate?
• How does the quality of lab equipment and resources affect test accuracy?
• Are animal tests ever repeated by other researchers to confirm the findings?
• How often is historical animal testing data reviewed for accuracy and relevance?
• How do researchers account for animal stress or discomfort in the test results?
• What role do third-party audits play in ensuring test accuracy?
• Do different labs or countries report differing levels of accuracy for similar tests?
• What’s the impact of using inbred animals on the accuracy of tests?
• How quickly does the scientific community adapt when new information challenges test accuracy?
• What is the impact of inaccurate animal testing on medical or product development timelines?
• What laws exist to protect animals in testing facilities?
• How often are animal testing labs inspected for compliance?
• What are the legal consequences for labs that mistreat animals?
• Are there international laws on animal testing, or do they vary by country?
• What kinds of animals are legally allowed to be used in testing, and are any species protected from being used?
• Do labs have to report how many animals they use and their living conditions?
• What are the requirements for pain management and the restrictions on the types of tests that can be done on animals under current regulations?
• How do laws differ for testing cosmetics versus medical products, and how are they enforced?
• Is it legally required to search for alternative methods before resorting to animal testing?
• What’s the process for a new law regarding animal testing to be passed, and is public opinion considered?
• Are there legal age or health restrictions for animals used in tests?
• Do companies have to disclose if they’ve tested a product on animals, and are animals used in testing required to be euthanized afterward by law?
• How transparent are labs required to be about their testing methods and results?
• What agencies are responsible for overseeing animal testing, and what legal protections exist for whistleblowers?
• How do animal welfare laws intersect with testing regulations, including the role of veterinarians?
• Are there special rules for universities and educational institutions conducting animal tests?
• What are the restrictions on transporting animals for lab testing, and how do these laws apply to imported goods?
• Are there ethical review boards that approve animal tests?
• What different regulations apply to short-term versus long-term tests?
• Can labs lose their license for repeated violations of animal welfare laws, and is there a legal requirement to report adverse effects observed during testing?
• Do companies clearly state their policies on animal testing?
• Are companies required to inform consumers if their products are tested on animals?
• How often do companies review and update their animal testing policies?
• Do companies have ethical review boards for their animal testing practices?
• Are employees trained on the ethical treatment of animals in testing?
• How transparent are companies about their use or non-use of alternative testing methods?
• Do companies collaborate with animal welfare organizations to improve their practices?
• Are companies’ animal testing policies influenced by where they operate or sell products?
• How do company policies differ for testing ingredients vs. finished products?
• What steps do companies take to minimize the number of animals used in tests?
• Are companies investing in research for alternative testing methods?
• Do companies give customers options for cruelty-free products?
• How do companies validate the claims of their suppliers about animal testing?
• Are there any third-party certifications that companies can get for ethical animal testing?
• How do companies handle public backlash or boycotts related to their animal testing practices?
• Do companies offer transparency reports related to their animal testing?
• Are companies’ animal testing policies influenced by their investors or shareholders?
• How do mergers and acquisitions affect a company’s animal testing policy?
• Do companies have plans to phase out animal testing in the future?
• How are companies adapting to legal changes that ban or limit animal testing?
• How often are animals checked for signs of stress or pain?
• What measures are taken to reduce animal suffering during tests?
• Are there veterinarians on site to monitor animal health?
• Do the animals get time to rest and recover between tests?
• Are the animals provided with social interaction to reduce stress?
• How are animals housed, and are their enclosures clean and safe?
• Do animals get regular exercise and stimulation?
• What kind of anesthesia or pain relief is given to animals during invasive tests?
• Are animals ever reused in multiple experiments?
• What happens to animals that get seriously sick or injured during tests?
• Are there “ humane endpoints ” to stop tests if animals suffer too much?
• How are animals fed, and is their diet appropriate for their species?
• How are the animals’ natural behaviors accommodated in the lab?
• What happens to the animals after the testing is complete?
• Is there an effort to use as few animals as possible in each test?
• Are any steps taken to rehabilitate animals after testing?
• Is there oversight to ensure animals are not being unnecessarily harmed?
• Are enrichment activities provided to keep animals mentally stimulated?
• How are lab workers trained to handle and care for animals?
• Are there protocols for humane euthanasia if needed?
• What are the most promising alternatives to animal testing?
• How effective are lab-grown tissues and organs for testing?
• Can computer simulations provide accurate data compared to animal tests?
• Why aren’t more companies or labs using alternatives to animal testing?
• Are alternatives to animal testing more expensive?
• How reliable are tests using human cells compared to animal tests?
• What’s stopping the widespread adoption of alternative testing methods?
• Are there any drawbacks to using alternatives like cell cultures?
• Can we trust the results from alternative methods?
• Do alternatives exist for all types of animal tests or just some?
• How long does it take for an alternative method to be approved for use?
• Are there any ethical concerns with the alternatives?
• How do different countries view alternative methods to animal testing?
• What research is being done to improve alternative methods?
• How do regulatory agencies validate the results from alternative testing?
• Is there a database where scientists can share findings from alternative methods?
• Are there educational programs focused on teaching alternative methods to animal testing?
• How much funding is dedicated to researching alternative methods?
• What role do animal welfare organizations play in promoting alternative methods?
• How can ordinary people advocate for the use of alternative methods?

What can I do if I’m concerned?

• Educate Yourself: The more you know, the better. • Speak Up: Talk about it with friends and family. • Support Organizations: Many groups are working to find alternatives and to improve conditions for animals.

How can I stay updated on this issue?

• Follow News: Stay informed with the latest articles and research. • Join Online Forums: Connect with like-minded individuals. • Attend Seminars or Webinars: Gain in-depth knowledge from experts.

To understand animal testing, we need to look beyond the surface. By asking specific questions, we can uncover the complexities of this issue and have a thoughtful conversation.

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Bea Mariel Saulo

Bea is an editor and writer with a passion for literature and self-improvement. Her ability to combine these two interests enables her to write informative and thought-provoking articles that positively impact society. She enjoys reading stories and listening to music in her spare time.

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Lives Saved, Lives Changed The Impact of Animal Research

• Why Animal Research?
• Animal Care

Frequently Asked Questions

• Additional Resources

How do humans benefit from animal research?

Animals are different from humans in many aspects, but there are also plenty of similarities, especially at the biological level. Certain fundamental processes, such as how cells and tissues work, are remarkably similar across animal species, including humans. The structures and functions of organs like the heart, lungs and brains, are also similar across most kinds of animals.

In 1953, Dr. Jonas Salk was present when it was publicly announced that the polio vaccine that he developed, using animal testing at the University of Pittsburgh, had been created. According to the World Health Organization, the number of polio cases has decreased by more than 99%, from an estimated 350,000 affected patients in 1988 to only 22 reported cases in 2017. Salk's vaccine has saved more than 16 million children from becoming paralyzed and prevented more than 1.5 million childhood deaths.

It is also important to conduct animal research to understand and predict the emergence of many "zoonotic" infectious diseases that spread between humans and animals, such as Lyme disease and rabies. The Human Immunodeficiency Virus (HIV), which causes AIDS, is thought to have first originated in nonhuman primates before spreading to humans. The bird flu epidemic is a more recent example of a zoonotic disease that evolved to infect humans.

Do animals benefit from this research?

Yes. Antibiotic and vaccine advancements have helped us prevent many devastating diseases in animals.

For example, Dr. Julius Youngner used the same techniques he used as a key contributor to the development of the polio vaccine at the University of Pittsburgh to create the first ever vaccine for equine influenza (horse flu) . Similarly, vaccines for rabies and treatments for heartworm infestation and cholera in dogs arose from animal research.

One of biggest success stories in veterinary science was the development of a vaccine for canine parvovirus. The highly contagious virus which caused significant death and suffering in dogs was first identified in 1978 and quickly spread around the world. Researchers found that parvovirus is similar to the feline panleukopenia virus, for which a vaccine was already available. Scientists used their knowledge about the existing vaccine to quickly create and test a new vaccine for dogs. The canine parvovirus vaccine stopped the spread of this disease and has since saved the lives of countless dogs.

The ability to treat diseases has also prevented the death of many endangered species and contributed to preservation efforts. Techniques developed through animal research such as artificial insemination and embryo transfer allow us to breed animals in captivity and help prevent the loss of at-risk animals.

What kinds of animals are used in research?

Animals are used in research only when no alternatives are available. Many different species may be used, including small animals such as rodents and guinea pigs, and large animals such as pigs, cats, dogs and nonhuman primates. The vast majority of animals used in research are rodents (mice and rats) and zebrafish. Based on estimates, 1% or less of the animals used in research are larger animals such as dogs, cats and nonhuman primates.

Why do clinical trials in humans require prior animal testing?

Animal testing is not an alternative to testing in humans. Rather, it is an important complementary part of the effort to find new therapies. It is important part of the process for two main reasons:

First it reduces the number of interventions tested. The development of treatments is a long and arduous process that starts with scientists testing hundreds or thousands of chemical compounds for the potential to treat a certain disease. Using various techniques including computer simulations and testing in lab-grown cells, they then narrow it down to a much smaller group of tens or hundreds of potential treatments. Since it is not possible or practical to test each candidate in a human trial, researchers use animals to determine those that are the most promising and can be further tested in human clinical trials.

The second major reason why animal testing is conducted prior to human clinical trials is to understand how a therapy works in the body and ensure that it does not have any significantly adverse effects. It is true that treatments that work in animals don't always work in humans. In fact, this is the outcome for a majority of candidates. However, it is important to note that a major goal of animal testing is to prevent harmful or highly toxic drugs from being tested in humans.

Can’t scientists use something other than animals?

In many cases, scientists can and do use research models other than animals. The most common alternative is cells cultured, or grown, in the laboratory.

Researchers, including those at the University of Pittsburgh, are also constantly striving to reduce the use of animals and develop alternative model systems. Organ-on-a-chip technology is one of the most promising advances in this regard, and Pitt's Drug Discovery Institute is a leader in the effort to develop such technology, which mimics human organs and can be used to test drugs.

These advances, however, are still in an early stage, and there are many areas of research that require the use of animals. Though computer simulations are being developed that could one day replace the use of animals, such technology is limited by the fact that we do not know enough about how the body works to create an effective and accurate simulation that can completely eliminate the use of animals.

Who cares for the animals used in research? Are they properly trained? How are the animals cared for?

Everyone who works with laboratory animals has a responsibility to care for their wellbeing. Specialized animal care technicians perform daily animal husbandry tasks, while dedicated veterinarians oversee the animals' physical and psychological health. The scientists who work with these animals are also closely engaged in their care. Researchers depend on robust animals to produce reliable results, so it is in everyone’s best interest to provide the best care possible for the animals.

According to federal regulations, no person can be listed on an active animal research protocol until they have completed required training. Every person who works with laboratory animals at Pitt is trained on proper research conduct, the responsibilities and regulations surrounding animal research in general, and the specific needs and considerations of the species with which they will be working. Recertification is required every four years. The Division of Laboratory Animal Resources oversees training and day-to-day regulatory compliance of animal research personnel.

In addition to their basic needs, such as food, water, and proper housing, laboratory animals are also provided with environmental enrichment to express more wild or natural behaviors, which decreases any detrimental mental or physical health effects that may result from caging. For instance, environmental enrichment could involve providing shelters and nesting materials to species that naturally nest, group housing or human interaction to social species, the ability to forage for food, and opportunities to play, climb, run, swim, or jump. Pitt has dedicated enrichment specialists who coordinate and oversee these efforts.

How is animal research at Pitt regulated?

The USDA , Office of Lab Animal Welfare ( OLAW ), and Association for Assessment and Accreditation of Laboratory Animal Care International ( AAALAC ) oversee animal research at the national level to ensure that all animal research is done in accordance with the Animal Welfare Act , The Guide for the Care and Use of Laboratory Animals , and the Public Health Service Policy on Humane Care and Use of Laboratory Animals. Internally, Pitt’s Institutional Animal Care and Use Committee ( IACUC ) reviews and approves all animal research protocols prior to the initiation of experiments. Periodically, the USDA, IACUC, and AAALAC inspect Pitt lab spaces and audit records to make sure that researchers and animal care staff are following the proper procedures. Serious infractions result in the suspension of research activities.

It is important to note that scientists use animals only when there are no alternatives available. Additionally, researchers using animals must adhere to strict policies and protocols that include providing rigorous justification for the need to conduct animal research, demonstrate that they have eliminated the possibility of using alternatives or included alternative approaches where possible, and use the fewest number of animals needed.

Has animal experimentation increased over time?

The USDA reports that over the past two decades research on large animals has been in decline. As of the 2016 USDA report, the number of large animals used in research is less than half of what it was in 1994. Overall, scientists in the U.S. use approximately 12-27 million animals in research, of which more than 90% are rats, mice, birds or fish.

To put these numbers in perspective: we use fewer animals in research than the number of ducks eaten per year in this country. We consume more than 1,800 times the number of pigs than the number used in research. We eat more than 340 chickens for each animal used in a research facility, and almost 9,000 chickens for every animal used in research covered by the Animal Welfare Act. For every animal used in research, it is estimated that 14 more are killed on our roads.

What happens to research animals once the experiment is completed?

Most animals under study must be euthanized to obtain tissue for further evaluation or for in vitro experiments. Euthanasia is the act of inducing a humane death, and the guidelines for proper euthanasia are established by The American Veterinary Medical Association .

Animals involved in experiments that do not require euthanasia may take part in additional experiments. Nonhuman primates, for example, can participate in many studies.

What is the difference between animal welfare and animal rights?

“Animal welfare,” as defined by the AVMA, is a human responsibility that encompasses all aspects of animal wellbeing, including proper housing, management, disease prevention and treatment, responsible care, humane handling, and, when necessary, humane euthanasia.

In contrast, “animal rights” is a philosophical view that animals have rights similar to or the same as humans. Many animal rights proponents believe that humans do not have the right to use animals for any purpose.

Animal research at Pitt abides by the principles of animal welfare.

Millions of people around the world have been given the opportunity to live a healthy life thanks to medical breakthroughs made possible through animal research here at the University of Pittsburgh and other research institutions.

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Open Access

Ethical and Scientific Considerations Regarding Animal Testing and Research

* E-mail: [email protected]

Affiliations Physicians Committee for Responsible Medicine, Washington, D.C., United States of America, Department of Medicine, The George Washington University, Washington, D.C., United States of America

Affiliation Physicians Committee for Responsible Medicine, Washington, D.C., United States of America

• Hope R. Ferdowsian, 

Published: September 7, 2011

• https://doi.org/10.1371/journal.pone.0024059
• Reader Comments

Citation: Ferdowsian HR, Beck N (2011) Ethical and Scientific Considerations Regarding Animal Testing and Research. PLoS ONE 6(9): e24059. https://doi.org/10.1371/journal.pone.0024059

Editor: Catriona J. MacCallum, Public Library of Science, United Kingdom

Copyright: © 2011 Ferdowsian, Beck. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The authors are grateful to the National Science Foundation (grant SES-0957163) and the Arcus Foundation (grant 0902-34) for the financial support for the corresponding conference, Animals, Research, and Alternatives: Measuring Progress 50 Years Later. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: HRF and NB are employed by Physicians Committee for Responsible Medicine, which is a non-governmental organization which promotes higher ethical standards in research and alternatives to the use of animals in research, education, and training. Physicians Committee for Responsible Medicine is a nonprofit organization, and the authors adhered to PLoS ONE policies on sharing data and materials.

In 1959, William Russell and Rex Burch published the seminal book, The Principles of Humane Experimental Technique, which emphasized r eduction, r efinement, and r eplacement of animal use, principles which have since been referred to as the “3 Rs”. These principles encouraged researchers to work to reduce the number of animals used in experiments to the minimum considered necessary, refine or limit the pain and distress to which animals are exposed, and replace the use of animals with non-animal alternatives when possible. Despite the attention brought to this issue by Russell and Burch and since, the number of animals used in research and testing has continued to increase, raising serious ethical and scientific issues. Further, while the “3 Rs” capture crucially important concepts, they do not adequately reflect the substantial developments in our new knowledge about the cognitive and emotional capabilities of animals, the individual interests of animals, or an updated understanding of potential harms associated with animal research. This Overview provides a brief summary of the ethical and scientific considerations regarding the use of animals in research and testing, and accompanies a Collection entitled Animals, Research, and Alternatives: Measuring Progress 50 Years Later , which aims to spur ethical and scientific advancement.

Introduction

One of the most influential attempts to examine and affect the use of animals in research can be traced back to1959, with the publication of The Principles of Humane Experimental Technique [1] . William Russell and Rex Burch published this seminal book in response to marked growth in medical and veterinary research and the concomitant increase in the numbers of animals used. Russell and Burch's text emphasized r eduction, r efinement, and r eplacement of animal use, principles which have since been referred to as the “3 Rs”. These principles encouraged researchers to work to reduce the number of animals used in experiments to the minimum considered necessary, refine or limit the pain and distress to which animals are exposed, and replace the use of animals with non-animal alternatives when possible.

Despite the attention brought to this issue by Russell and Burch, the number of animals used in research and testing has continued to increase. Recent estimates suggest that at least 100 million animals are used each year worldwide [2] . However, this is likely an underestimate, and it is impossible to accurately quantify the number of animals used in or for experimentation. Full reporting of all animal use is not required or made public in most countries. Nevertheless, based on available information, it is clear that the number of animals used in research has not significantly declined over the past several decades.

The “3 Rs” serve as the cornerstone for current animal research guidelines, but questions remain about the adequacy of existing guidelines and whether researchers, review boards, and funders have fully and adequately implemented the “3 Rs”. Further, while the “3 Rs” capture crucially important concepts, they do not adequately reflect the substantial developments in our new knowledge about the cognitive and emotional capabilities of animals; an updated understanding of the harms inherent in animal research; and the changing cultural perspectives about the place of animals in society [3] , [4] . In addition, serious questions have been raised about the effectiveness of animal testing and research in predicting anticipated outcomes [5] – [13] .

In August 2010, the Georgetown University Kennedy Institute of Ethics, the Johns Hopkins University Center for Alternatives to Animal Testing, the Institute for In Vitro Sciences, The George Washington University, and the Physicians Committee for Responsible Medicine jointly held a two day multi-disciplinary, international conference in Washington, DC, to address the scientific, legal, and political opportunities and challenges to implementing alternatives to animal research. This two-day symposium aimed to advance the study of the ethical and scientific issues surrounding the use of animals in testing and research, with particular emphasis on the adequacy of current protections and the promise and challenges of developing alternatives to the use of animals in basic research, pharmaceutical research and development, and regulatory toxicology. Speakers who contributed to the conference reviewed and contributed new knowledge regarding the cognitive and affective capabilities of animals, revealed through ethology, cognitive psychology, neuroscience, and related disciplines. Speakers also explored the dimensions of harm associated with animal research, touching on the ethical implications regarding the use of animals in research. Finally, several contributors presented the latest scientific advances in developing alternatives to the use of animals in pharmaceutical research and development and regulatory toxicity testing.

This Collection combines some papers that were written following this conference with an aim to highlight relevant progress and research. This Overview provides a brief summary of the ethical and scientific considerations regarding the use of animals in research and testing, some of which are highlighted in the accompanying Collection.

Analysis and Discussion

Ethical considerations and advances in the understanding of animal cognition.

Apprehension around burgeoning medical research in the late 1800s and the first half of the 20 th century sparked concerns over the use of humans and animals in research [14] , [15] . Suspicions around the use of humans were deepened with the revelation of several exploitive research projects, including a series of medical experiments on large numbers of prisoners by the Nazi German regime during World War II and the Tuskegee syphilis study. These abuses served as the impetus for the establishment of the Nuremberg Code, Declaration of Helsinki, and the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research (1974) and the resulting Belmont Report [16] – [18] . Today, these guidelines provide a platform for the protection of human research subjects, including the principles of respect, beneficence, and justice, as well as special protections for vulnerable populations.

Laws to protect animals in research have also been established. The British Parliament passed the first set of protections for animals in 1876, with the Cruelty to Animals Act [19] . Approximately ninety years later, the U.S. adopted regulations for animals used in research, with the passage of the Laboratory Animal Welfare Act of 1966 [20] . Subsequent national and international laws and guidelines have provided basic protections, but there are some significant inconsistencies among current regulations [21] . For example, the U.S. Animal Welfare Act excludes purpose-bred birds, rats, or mice, which comprise more than 90% of animals used in research [20] . In contrast, certain dogs and cats have received special attention and protections. Whereas the U.S. Animal Welfare Act excludes birds, rats and mice, the U.S. guidelines overseeing research conducted with federal funding includes protections for all vertebrates [22] , [23] . The lack of consistency is further illustrated by the “U.S. Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research and Training” which stress compliance with the U.S. Animal Welfare Act and “other applicable Federal laws, guidelines, and policies” [24] .

While strides have been made in the protection of both human and animal research subjects, the nature of these protections is markedly different. Human research protections emphasize specific principles aimed at protecting the interests of individuals and populations, sometimes to the detriment of the scientific question. This differs significantly from animal research guidelines, where the importance of the scientific question being researched commonly takes precedence over the interests of individual animals. Although scientists and ethicists have published numerous articles relevant to the ethics of animal research, current animal research guidelines do not articulate the rationale for the central differences between human and animal research guidelines. Currently, the majority of guidelines operate on the presumption that animal research should proceed based on broad, perceived benefits to humans. These guidelines are generally permissive of animal research independent of the costs to the individual animal as long as benefits seem achievable.

The concept of costs to individual animals can be further examined through the growing body of research on animal emotion and cognition. Studies published in the last few decades have dramatically increased our understanding of animal sentience, suggesting that animals' potential for experiencing harm is greater than has been appreciated and that current protections need to be reconsidered. It is now widely acknowledged by scientists and ethicists that animals can experience pain and distress [25] – [29] . Potential causes of harm include invasive procedures, disease, and deprivation of basic physiological needs. Other sources of harm for many animals include social deprivation and loss of the ability to fulfill natural behaviors, among other factors. Numerous studies have demonstrated that, even in response to gentle handling, animals can show marked changes in physiological and hormonal markers of stress [30] .

Although pain and suffering are subjective experiences, studies from multiple disciplines provide objective evidence of animals' abilities to experience pain. Animals demonstrate coordinated responses to pain and many emotional states that are similar to those exhibited by humans [25] , [26] . Animals share genetic, neuroanatomical, and physiological similarities with humans, and many animals express pain in ways similar to humans. Animals also share similarities with humans in genetic, developmental, and environmental risk factors for psychopathology [25] , [26] . For example, fear operates in a less organized subcortical neural circuit than pain, and it has been described in a wide variety of species [31] . More complex markers of psychological distress have also been described in animals. Varying forms of depression have been repeatedly reported in animals, including nonhuman primates, dogs, pigs, cats, birds and rodents, among others [32] – [34] . Anxiety disorders, such as post-traumatic stress disorder, have been described in animals including chimpanzees and elephants [35] , [36] , [37] .

In addition to the capacity to experience physical and psychological pain or distress, animals also display many language-like abilities, complex problem-solving skills, tool related cognition and pleasure-seeking, with empathy and self-awareness also suggested by some research. [38] – [44] . Play behavior, an indicator of pleasure, is widespread in mammals, and has also been described in birds [45] , [46] . Behavior suggestive of play has been observed in other taxa, including reptiles, fishes and cephalopods [43] . Self-awareness, assessed through mirror self-recognition, has been reported for chimpanzees and other great apes, magpies, and some cetaceans. More recent studies have shown that crows are capable of creating and using tools that require access to episodic-like memory formation and retrieval [47] . These findings suggest that crows and related species display evidence of causal reasoning, flexible learning strategies, imagination and prospection, similar to findings in great apes. These findings also challenge our assumptions about species similarities and differences and their relevance in solving ethical dilemmas regarding the use of animals in research.

Predictive Value of Animal Data and the Impact of Technical Innovations on Animal Use

In the last decade, concerns have mounted about how relevant animal experiments are to human health outcomes. Several papers have examined the concordance between animal and human data, demonstrating that findings in animals were not reliably replicated in human clinical research [5] – [13] . Recent systematic reviews of treatments for various clinical conditions demonstrated that animal studies have been poorly predictive of human outcomes in the fields of neurology and vascular disease, among others [7] , [48] . These reviews have raised questions about whether human diseases inflicted upon animals sufficiently mimic the disease processes and treatment responses seen in humans.

The value of animal use for predicting human outcomes has also been questioned in the regulatory toxicology field, which relies on a codified set of highly standardized animal experiments for assessing various types of toxicity. Despite serious shortcomings for many of these assays, most of which are 50 to 60 years old, the field has been slow to adopt newer methods. The year 2007 marked a turning point in the toxicology field, with publication of a landmark report by the U.S. National Research Council (NRC), highlighting the need to embrace in vitro and computational methods in order to obtain data that more accurately predicts toxic effects in humans. The report, “Toxicity Testing in the 21 st Century: A Vision and a Strategy,” was commissioned by the U.S. Environmental Protection Agency, partially due to the recognition of weaknesses in existing approaches to toxicity testing [49] . The NRC vision calls for a shift away from animal use in chemical testing toward computational models and high-throughput and high-content in vitro methods. The report emphasized that these methods can provide more predictive data, more quickly and affordably than traditional in vivo methods. Subsequently published articles address the implementation of this vision for improving the current system of chemical testing and assessment [50] , [51] .

While a sea change is underway in regulatory toxicology, there has been much less dialogue surrounding the replacement of animals in research, despite the fact that far more animals are used in basic and applied research than in regulatory toxicology. The use of animals in research is inherently more difficult to approach systematically because research questions are much more diverse and less proscribed than in regulatory toxicology [52] . Because researchers often use very specialized assays and systems to address their hypotheses, replacement of animals in this area is a more individualized endeavour. Researchers and oversight boards have to evaluate the relevance of the research question and whether the tools of modern molecular and cell biology, genetics, biochemistry, and computational biology can be used in lieu of animals. While none of these tools on their own are capable of replicating a whole organism, they do provide a mechanistic understanding of molecular events. It is important for researchers and reviewers to assess differences in the clinical presentation and manifestation of diseases among species, as well as anatomical, physiological, and genetic differences that could impact the transferability of findings. Another relevant consideration is how well animal data can mirror relevant epigenetic effects and human genetic variability.

Examples of existing and promising non-animal methods have been reviewed recently by Langley and colleagues, who highlighted advances in fields including orthodontics, neurology, immunology, infectious diseases, pulmonology, endocrine and metabolism, cardiology, and obstetrics [52] .

Many researchers have also begun to rely solely on human data and cell and tissue assays to address large areas of therapeutic research and development. In the area of vaccine testing and development, a surrogate in-vitro human immune system has been developed to help predict an individual's immune response to a particular drug or vaccine [53] , [54] . This system includes a blood-donor base of hundreds of individuals from diverse populations and offers many benefits, including predictive high-throughput in vitro immunology to assess novel drug and vaccine candidates, measurement of immune responses in diverse human populations, faster cycle time for discovery, better selection of drug candidates for clinical evaluation, and reductions in the time and costs to bring drugs and vaccines to the market. In the case of vaccines, this system can be used at every stage, including in vitro disease models, antigen selection and adjuvant effects, safety testing, clinical trials, manufacturing, and potency assays. When compared with data from animal experiments, this system has produced more accurate pre-clinical data.

The examples above illustrate how innovative applications of technology can generate data more meaningful to humans, and reduce or replace animal use, but advances in medicine may also require novel approaches to setting research priorities. The Dr. Susan Love Research Foundation, which focuses on eradicating breast cancer, has challenged research scientists to move from animal research to breast cancer prevention research involving women. If researchers could better understand the factors that increase the risk for breast cancer, as well as methods for effective prevention, fewer women would require treatment for breast cancer. Whereas animal research is largely investigator-initiated, this model tries to address the questions that are central to the care of women at risk for or affected by breast cancer. This approach has facilitated the recruitment of women for studies including a national project funded by the National Institutes of Health and the National Institute of Environmental Health to examine how environment and genes affect breast cancer risk. This study, which began in 2002, could not have been accomplished with animal research [55] .

Similarly, any approach that emphasizes evidence-based prevention would provide benefits to both animals and humans. Resource limitations might require a strategic approach that emphasizes diseases with the greatest public health threats, which increasingly fall within the scope of preventable diseases.

It is clear that there have been many scientific and ethical advances since the first publication of Russell and Burch's book. However, some in the scientific community are beginning to question how well data from animals translates into germane knowledge and treatment of human conditions. Efforts to objectively evaluate the value of animal research for understanding and treating human disease are particularly relevant in the modern era, considering the availability of increasingly sophisticated technologies to address research questions [9] . Ethical objections to the use of animals have been publically voiced for more than a century, well before there was a firm scientific understanding of animal emotion and cognition [15] . Now, a better understanding of animals' capacity for pain and suffering is prompting many to take a closer look at the human use of animals [56] .

Articles in the accompanying Collection only briefly touch on the many scientific and ethical issues surrounding the use of animals in testing and research. While it is important to acknowledge limitations to non-animal methods remain, recent developments demonstrate that these limitations should be viewed as rousing challenges rather than insurmountable obstacles. Although discussion of these issues can be difficult, progress is most likely to occur through an ethically consistent, evidence-based approach. This collection aims to spur further steps forward toward a more coherent ethical framework for scientific advancement.

Acknowledgments

The authors thank the conference speakers and participants for their participation.

Author Contributions

Conceived and designed the experiments: HRF NB. Contributed reagents/materials/analysis tools: HRF NB. Wrote the paper: HRF NB.

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• Published: 27 September 2023

The well-built research question

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How to reduce animal numbers and increase the information content of animal-based studies. A ‘well-built’ research question turns the research hypothesis into an actionable, focused, and testable plan of action.

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About Animal Testing

Humane Society International / Global

What is animal testing?

The term “animal testing” refers to procedures performed on living animals for purposes of research into basic biology and diseases, assessing the effectiveness of new medicinal products, and testing the human health and/or environmental safety of consumer and industry products such as cosmetics, household cleaners, food additives, pharmaceuticals and industrial/agro-chemicals. All procedures, even those classified as “mild,” have the potential to cause the animals physical as well as psychological distress and suffering. Often the procedures can cause a great deal of suffering. Most animals are killed at the end of an experiment, but some may be re-used in subsequent experiments. Here is a selection of common animal procedures:

• Forced chemical exposure in toxicity testing, which can include oral force-feeding, forced inhalation, skin or injection into the abdomen, muscle, etc.
• Exposure to drugs, chemicals or infectious disease at levels that cause illness, pain and distress, or death
• Genetic manipulation, e.g., addition or “knocking out” of one or more genes
• Ear-notching and tail-clipping for identification
• Short periods of physical restraint for observation or examination
• Prolonged periods of physical restraint
• Food and water deprivation
• Surgical procedures followed by recovery
• Infliction of wounds, burns and other injuries to study healing
• Infliction of pain to study its physiology and treatment
• Behavioural experiments designed to cause distress, e.g., electric shock or forced swimming
• Other manipulations to create “animal models” of human diseases ranging from cancer to stroke to depression
• Killing by carbon dioxide asphyxiation, neck-breaking, decapitation, or other means

What types of animals are used?

Many different species are used around the world, but the most common include mice, fish, rats, rabbits, guinea pigs, hamsters, farm animals, birds, cats, dogs, mini-pigs, and non-human primates (monkeys, and in some countries, chimpanzees). Video: Watch what scientists have to say about alternatives to animal testing .

It is estimated that more than 115 million animals worldwide are used in laboratory experiments every year. But because only a small proportion of countries collect and publish data concerning animal use for testing and research, the precise number is unknown. For example, in the United States, up to 90 percent of the animals used in laboratories (purpose-bred rats, mice and birds, fish, amphibians, reptiles and invertebrates) are excluded from the official statistics, meaning that figures published by the U.S. Department of Agriculture are no doubt a substantial underestimate.

Within the European Union, more than 12 million animals are used each year, with France, Germany and the United Kingdom being the top three animal using countries. British statistics reflect the use of more than 3 million animals each year, but this number does not include animals bred for research but killed as “surplus” without being used for specific experimental procedures. Although these animals still endure the stresses and deprivation of life in the sterile laboratory environment, their lives are not recorded in official statistics. HSI believes that complete transparency about animal use is vital and that all animals bred, used or killed for the research industry should be included in official figures. See some animal use statistics .

What’s wrong with animal testing?

For nearly a century, drug and chemical safety assessments have been based on laboratory testing involving rodents, rabbits, dogs, and other animals. Aside from the ethical issues they pose—inflicting both physical pain as well as psychological distress and suffering on large numbers of sentient creatures—animal tests are time- and resource-intensive, restrictive in the number of substances that can be tested, provide little understanding of how chemicals behave in the body, and in many cases do not correctly predict real-world human reactions. Similarly, health scientists are increasingly questioning the relevance of research aimed at “modelling” human diseases in the laboratory by artificially creating symptoms in other animal species.

Trying to mirror human diseases or toxicity by artificially creating symptoms in mice, dogs or monkeys has major scientific limitations that cannot be overcome. Very often the symptoms and responses to potential treatments seen in other species are dissimilar to those of human patients. As a consequence, nine out of every 10 candidate medicines that appear safe and effective in animal studies fail when given to humans. Drug failures and research that never delivers because of irrelevant animal models not only delay medical progress, but also waste resources and risk the health and safety of volunteers in clinical trials.

What’s the alternative?

If lack of human relevance is the fatal flaw of “animal models,” then a switch to human-relevant research tools is the logical solution. The National Research Council in the United States has expressed its vision of “a not-so-distant future in which virtually all routine toxicity testing would be conducted in human cells or cell lines”, and science leaders around the world have echoed this view.

The sequencing of the human genome and birth of functional genomics, the explosive growth of computer power and computational biology, and high-speed robot automation of cell-based (in vitro) screening systems, to name a few, has sparked a quiet revolution in biology. Together, these innovations have produced new tools and ways of thinking that can help uncover exactly how chemicals and drugs disrupt normal processes in the human body at the level of cells and molecules. From there, scientists can use computers to interpret and integrate this information with data from human and population-level studies. The resulting predictions regarding human safety and risk are potentially more relevant to people in the real world than animal tests.

But that’s just the beginning. The wider field of human health research could benefit from a similar shift in paradigm. Many disease areas have seen little or no progress despite decades of animal research. Some 300 million people currently suffer from asthma, yet only two types of treatment have become available in the last 50 years. More than a thousand potential drugs for stroke have been tested in animals, but only one of these has proved effective in patients. And it’s the same story with many other major human illnesses. A large-scale re-investment in human-based (not mouse or dog or monkey) research aimed at understanding how disruptions of normal human biological functions at the levels of genes, proteins and cell and tissue interactions lead to illness in our species could advance the effective treatment or prevention of many key health-related societal challenges of our time.

Modern non-animal techniques are already reducing and superseding experiments on animals, and in European Union, the “3Rs” principle of replacement, reduction and refinement of animal experiments is a legal requirement. In most other parts of the world there is currently no such legal imperative, leaving scientists free to use animals even where non-animal approaches are available.

If animal testing is so unreliable, why does it continue?

Despite this growing evidence that it is time for a change, effecting that change within a scientific community that has relied for decades on animal models as the “default method” for testing and research takes time and perseverance. Old habits die hard, and globally there is still a lack of knowledge of and expertise in cutting-edge non-animal techniques.

But with HSI’s help, change is happening. We are leading efforts globally to encourage scientists, companies and policy-makers to transition away from animal use in favour of 21st century methods. Our work brings together experts from around the globe to share knowledge and best practice, improving the quality of research by replacing animals in the laboratory.

Are animal experiments needed for medical progress?

It is often argued that because animal experiments have been used for centuries, and medical progress has been made in that time, animal experiments must be necessary. But this is missing the point. History is full of examples of flawed or basic practices and ideas that were once considered state-of-the-art, only to be superseded years later by something far more sophisticated and successful. In the early 1900’s, the Wright brothers’ invention of the airplane was truly innovative for its time, but more than a century later, technology has advanced so much that when compared to the modern jumbo jet those early flying machines seem quaint and even absurd. Those early ideas are part of aviation history, but no-one would seriously argue that they represent the cutting-edge of design or human achievement. So it is with laboratory research. Animal experiments are part of medical history, but history is where they belong. Compared to today’s potential to understand the basis of human disease at cellular and molecular levels, experimenting on live animals seems positively primitive. So if we want better quality medical research, safer more effective pharmaceuticals and cures to human diseases, we need to turn the page in the history books and embrace the new chapter—21st century science.

Independent scientific reviews demonstrate that research using animals correlates very poorly to real human patients. In fact, the data show that animal studies fail to predict real human outcomes in 50 to 99.7 percent of cases. This is mainly because other species seldom naturally suffer from the same diseases as found in humans. Animal experiments rely on often uniquely human conditions being artificially induced in non-human species. While on a superficial level they may share similar symptoms, fundamental differences in genetics, physiology and biochemistry can result in wildly different reactions to both the illness and potential treatments. For some areas of disease research, overreliance on animal models may well have delayed medical progress rather than advanced it. By contrast, many non-animal replacement methods such as cell-based studies, silicon chip biosensors, and computational systems biology models, can provide faster and more human-relevant answers to medical and chemical safety questions that animal experiments cannot match.

“The claim that animal experimentation is essential to medical development is not supported by proper, scientific evidence but by opinion and anecdote. Systematic reviews of its effectiveness don’t support the claims made on its behalf” (Pandora Pound et al. British Medical Journal 328, 514-7, 2004).

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Imagine a syringe being forced down your throat to inject a chemical into your stomach, or being restrained and forced to breathe sickening vapours for hours. That’s the cruel reality of animal testing for millions of mice, rabbits, dogs and other animals worldwide.

We’re giving the beauty industry a cruelty-free makeover with a wave of animal testing bans supported by hundreds of companies and millions of caring consumers worldwide.

We all dream of the day when cancer is cured and AIDS is eradicated, but is the continued use of mice, monkeys and other animals as experimental “models” of human disease actually holding us back from realizing the promise of 21st century science?

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Student Opinion

What Is Our Responsibility to Lab Animals?

Standard ethical guidelines encourage minimizing the use of, and harm to, animals in research. Is that enough?

By Jeremy Engle

Scientists use animals to learn more about diseases, develop drugs and test product safety. For example, Covid-19 vaccines were tested on mice and monkeys and developed based on decades of animal-based work on mRNA vaccine technology. The results saved an estimated 20 million lives.

Standard ethical guidelines encourage minimizing the use of, and harm to, animals in research. But the question remains: Is that enough?

Proponents of animal testing argue that the benefits are enormous and justify the harms to animals. Opponents assert that animal testing is unethical and that the benefits are overstated. And some experts contend that, so long as animals are used in research — which they probably will be for years to come — humans owe them more: repayment.

What do you think?

In “ What Do We Owe Lab Animals? ” Brandon Keim reports on the issue of repayment:

When Lauren Strohacker received her second Covid-19 vaccine dose in the spring of 2021, she rejoiced. It meant she could see her friends again, go to concerts and live with far less fear that an infection might leave her physically or financially devastated. But it became a bittersweet memory. Not long after Ms. Strohacker, an artist based in Knox County, Tenn., returned home from the vaccination site, she read an article about monkeys used in testing Covid vaccines. “I thought, I’m afraid of a stupid needle,” she said. “And these animals have to deal with this all the time.” She reflected on how her newfound freedom, and quite possibly her health, came at the expense of animals suffering or dying to develop the vaccines. Merely being grateful for those animals seemed insufficient; Ms. Strohacker wanted to give something tangible in return. A little online research returned the National Anti-Vivisection Society’s sanctuary fund, which supports the care of retired lab animals. She made a small donation. “To give thanks was the very least I could do,” Ms. Strohacker said. Her gesture embodies a voice that is not often heard in debates about the use of animals in biomedical research. These tend to be polarized between opponents of the research , who claim that it is unethical and the benefits are overstated, and proponents who argue that the benefits are enormous and justify the harms to animals. The advancement of animal-free methods for developing drugs and testing product safety does raise the possibility that, at least in some cases, the use of animals can be avoided. But it will take years for that to happen, and few researchers think the use of animals will cease altogether. So long as animals are used, then, the question remains: What do people owe them?

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Ethical care for research animals

FACTS and MYTHS

You've heard the myths about animals and research science. We'd like to share some of the facts.

Myth: cats, dogs, and primates are the animals most used in research., fact: approximately 95% of the total number of animals needed for medical and scientific inquiry in the u.s. are rodents..

Most of the animals needed for medical and scientific inquiry in the U.S. are rodents (for example, rats and mice), and they are specifically bred for this purpose.

Dogs, cats, and nonhuman primates together account for less than 1% of all animals necessary for medical research. A wide variety of other species make up the remaining 4%, from eels, to armadillos, to zebrafish, to frogs.

Myth: Research animals are abused and mistreated.

Fact: good science and good animal care are inseparable..

If animals are not well treated, the science and knowledge from their studies will not be trustworthy and cannot be replicated, both important hallmarks of the scientific method.  

Our researchers are strong supporters of animal welfare, and view their work with animals as a privilege. They are legally, and morally, obligated to ensure the health and well-being of all animals in their care in strict adherence to federal and state regulatory guidelines and humane principles, and to ensure that our animals are involved only in productive and meaningful studies.

Myth: Animal research is scientific fraud, since animals and humans are different.

Fact: there are many similarities between humans and animals..

For example, chimpanzees share more that 99% of DNA with humans, and mice share more than 98%!  Animals are susceptible to many of the same health problems as humans – cancer, diabetes, and heart disease, to name a few.

Research with animal species has provided much of what we know about disease progression, care, treatment, and cure. For example, mice have significantly contributed to the advances in the treatment and survival of breast cancer; zebrafish are excellent models for the study of hemophilia; and cats have helped us know more about disorders such as Sudden Infant Death Syndrome (SIDS), sleep apnea, and epilepsy.

Myth: Animal research is no longer necessary because there are non-animal alternatives to animal experiments.

Fact: researchers are committed to the search for alternatives to animal use whenever possible, for ethical, humane, and economic reasons, and a wide-variety of alternative techniques are actively utilized..

Such alternatives include cell-culture techniques, animal or human serum (a derivative of blood), and computer modeling, among others. All together, these alternative research methodologies play an important and growing role in biomedical research. They cannot, however, reproduce the interactions of an intact, whole-living biological system provided by laboratory animals, nor can they reveal potential complications from a drug designed to treat one condition on other organs and systems.

Legally, animal use is a required part of drug development.  Current U.S. federal laws and regulations require proof of safety and effectiveness through testing in animal models before any human studies (clinical trials) are allowed to begin.  No new drug may be prescribed in the United States without successful completion of human clinical trials and approval by the FDA.  

With all the promise and information alternatives to animal-based research offers, it cannot yet fully replace whole-animal models in any comprehensive fashion.

Myth: Animal testing debates argue that animal experiments are needlessly duplicated.

Fact: researchers are committed to preventing any unnecessary duplication of experiments..

The rigorous scientific peer review of research proposals, extensive literature searches, and the study of previous experiments helps researchers prevent duplication.

In addition to the ethical imperative to avoid duplication, there are economic incentives as well. Animal research is expensive and avoiding duplicate experimentation is cost-effective as well as ethically sound. Competition for funding also ensures that redundant experiments are unlikely to be approved, that projects have been evaluated to determine whether animals are necessary, and that the absolute minimum number of animals is used.

Myth: Millions of stolen pets are sold for research.

Fact: animals used for research do not come from random animal dealers who steal dogs and cats for research..

In California, dogs and cats needed for medical research are obtained from specialty laboratory animal breeders, who are registered with the USDA. These specially bred animals are chosen for their genetic make-up, health condition, and breed, something that could not be achieved using animals from pounds or shelters, or from individuals with non-laboratory-bred animals. All dogs and cats must have paperwork that clearly demonstrates their point of origin, to ensure and prove that these animals have never been pets.

Animal Research species at Stanford. Click for larger view.

Good animal care = good science.

Mice share 98% of their DNA with humans!

Animal trials are federally mandated.

Alternative techniques are used whenever possible.

Stanford veterinarians caring for research animals.

Regulatory Oversight

Stanford researchers keep to the highest standards of animal care and oversight.

• Learn more about research oversight

Animal Well-Being

The well-being of the animals in our care is of paramount importance at Stanford.

• Are animals treated ethically at Stanford? Learn more

Animal Care and Facilities

All research animals at Stanford live in environments that meet their specific, species-associated needs.

• Learn more about species-specific care

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• Future Perfect

Animal testing, explained

Is anything really “cruelty-free”?

by Celia Ford

It’s nearly impossible to go a day without benefitting from the suffering of animals. The ingredients in your toiletries and makeup; your medicine, vaccines, and implants; your cleaning supplies; the chemicals that helped grow your food — most of it was, at some point, tested on animals.

For centuries, the biological sciences have relied on animal testing. To figure out how a machine works, you need to disassemble it and check out its component parts. Understanding the living body, one of nature’s most complex and beautiful machines, is no different. Taking apart and fiddling with a toaster doesn’t hurt anyone, but dismantling a biological system certainly does.

Many scientists believe that experimenting on living animals is a necessary means of solving problems that affect both humans and animals. But these experiments often involve animals experiencing distress, whether from the side effects of an experimental drug, an intentionally inflicted illness, or simply their confined living situation. Some lucky lab animals get to spend their retirement in sanctuaries once they’re no longer needed. Most of the time, the animal dies, either as a direct consequence of the experiment or from euthanasia.

More often than not, animal research happens behind closed, locked, unmarked doors. That lack of transparency makes it difficult to know what to think about animal testing, and public opinion is tellingly divided. A 2018 Pew Research Center survey found that 47 percent of people in the US support the use of animals in scientific research, and 52 percent oppose it. Unlike climate change or reproductive health , where the parties are highly polarized, animal testing is one of few science-related policy issues where the attitudes of Republicans and Democrats are pretty similar: Both parties are split roughly 50-50.

Experimenting on animals places two seemingly good things — medical innovation and animal welfare — at odds. Even those who support animal research generally hold nuanced, conflicted beliefs about it, and questions about the nature and extent of animal testing are still hotly debated.

Inside this story

• What animal testing actually does
• Who is looking out for the welfare of animals
• The truth behind labels like “cruelty-free”
• The future of animal-free testing

Brands frequently mislead consumers about animal testing involving their products with vague labeling, and alternative research methods aren’t as broadly applicable as some activist organizations imply . Meanwhile, research facilities often ban employees from sharing photos of lab animals without institutional approval and rarely let the media observe experiments for themselves.

After spending six years as a neuroscience PhD student working in a lab with monkeys, I left academia with the impression that animal testing is neither as well-managed or justified as regulators claim, nor as malicious as others fear. Government agencies are starting to direct funding toward finding alternatives to animal testing, but the use of animals is deeply embedded in biological sciences.

A world without lab animals may be possible, but we don’t live in it yet. Here’s what’s actually going on.

What is animal testing?

Before humans invented microscopes, universities, or even paper, we were using animals for medical research. Over two millennia ago , ancient Greek philosopher Aristotle dissected dozens of animal species to better understand their anatomy and argued that studying their bodies could teach us a lot about our own biology. Over four centuries later, Galen of Pergamon , one of the most pivotal characters in Western medical history, performed public surgeries on animals ( especially monkeys ) for science, providing a spectacle that attracted curious audiences.

Today, animal experimentation is widespread and conducted far from the public eye. It falls under two broad, semi-overlapping umbrellas: biomedical research (which aims to understand, prevent, and treat diseases, as well as uncover fundamental information about how bodies work) and toxicology , or testing the effects of chemicals (including everything from toothpaste and makeup to pesticides) on living things.

Humans generally don’t want to be proverbial guinea pigs for new medicines or consumer products. We’d rather know that things are safe before we put them anywhere near our bodies. Companies, whether they deal in cosmetics or pharmaceuticals, also don’t want to be liable for poisoning their customers.

People can participate in experiments that might harm them, but historically, at best, such projects have been difficult to administer . At worst, they have involved illegal human experimentation that cast a long, dark shadow over the field of medical research.

The Tuskegee syphilis study , for example, put hundreds of poor Black men with untreated syphilis through decades of invasive tests in exchange for hot meals and basic medical treatment, just to see how the disease would progress if left untreated. Effective treatments became available during the study, but researchers withheld them. Once the experiment’s scandalous history was publicly disclosed in 1972 , the US government formalized basic ethical guidelines for human research and required Institutional Review Boards (IRBs) to approve studies on humans.

Today, many questions — like What is the lethal dose of this new drug? and Does this new surgical technique actually work? — can’t ethically be asked regarding humans without first being tested on a nonhuman subject.

For a long time, animals were the only alternative to humans available. To figure out the lethal dose of a new drug, scientists can give increasingly large amounts of it to mice and see what it takes to kill them. To test whether a brain implant actually relieves Parkinson’s symptoms, scientists do brain surgery on monkeys . Without computational models or cell cultures sophisticated enough to mimic the complicated interactions between organs, the options have historically been to use animals as a proxy or to drop or scale back your planned research.

We can only guess how many animals are being used in scientific experiments worldwide. The United States Department of Agriculture (USDA) publishes official reports on animal research every year, but they only include animals protected by the Animal Welfare Act (AWA), the federal law setting basic standards for the treatment and housing of certain farm animals and lab animals. The law covers dogs, cats, monkeys, guinea pigs, hamsters, pigs, rabbits, and sheep. In 2019, about 800,000 animals protected by AWA were used in research — 930,000, if you add those that lived in labs but were never included in a study.

Notably, the AWA doesn’t apply to mice and rats, which several studies estimate account for somewhere between 93 and 99 percent of all lab animals in the US. The AWA also excludes invertebrates like flies, worms, fish, and cephalopods like octopuses, whose intelligence makes them intriguing neuroscience subjects. The EU, which counts all vertebrates used in experiments, tallied about 10.6 million animals used in 2017. It’s harder to pin down a number in the US. Depending on who you ask , there might be 10 million rodents subjected to scientific experiments annually, or there might be 111 million. (Either way, it’s more than three times the number of rats in New York City.)

Rodents make appealing animal models for many scientists because they’re smart enough to learn simple tasks but are still socially regarded as pests; those who kill rats for a living don’t face the same kind of backlash as someone who, say, boasts about shooting a puppy . Nearly all mouse genes share functions with human genes, so at a basic level, their biology resembles ours. Mice only live for a year or two, enabling scientists to study things like chronic disease progression without waiting an entire human lifespan. And scientists can genetically alter mice in countless ways, knocking out or adding DNA to express diseases or make certain cell types glow under a microscope.

In some cases, a research question requires invasively studying a full, living biological system, but the gap between mice and humans is too wide. The USDA reported that 68,257 monkeys were used in 2019 to study subjects like SARS-CoV-2 , Parkinson’s disease , and HIV , where physiological and cognitive similarity to humans was a priority. Those primates were mostly macaques and marmosets; the use of chimpanzees (our closest ape relative) is now banned in many countries , including the US .

But monkey research may not be viable much longer. While hundreds of monkey experiments are being funded by the NIH , there aren’t enough long-tailed macaques to go around. In a desperate attempt to keep up with skyrocketing demand, thousands of wild-caught monkeys are illegally imported to US research institutions from countries like Cambodia. Two years ago, the long-tailed macaque was listed as endangered for the first time. PETA petitioned the US government to protect the species under the Endangered Species Act , which could end their use in research altogether, but the request has yet to be approved. Most people are uncomfortable with the idea of experimenting on an animal so similar to us, including some of the scientists who do it. However, many scientists and policymakers agree that we still don’t have non-animal alternatives that can answer tough research questions involving interactions between organs. Researchers worry that the looming primate shortage in the US — engendered by transportation restrictions and therapeutic testing requirements and exacerbated by pandemic-era demands — will limit our ability to respond to public health emergencies.

Monkeys are traditionally recognized as the only nonhuman animals that react to drugs with human-specific targets, meaning that in some cases, their body’s reactions could uniquely predict whether a drug will be safe and effective for humans. During the first years of the Covid-19 pandemic, monkeys were considered so crucial to SARS-CoV-2 research that when the rhesus macaque supply dried up, scientists didn’t turn to cell cultures or computer models — they just looked for different monkeys .

You might not agree that this research justifies the nonconsensual use of highly intelligent animals; many don’t, for both ethical and scientific reasons. But it’s happening, and if you’ve been vaccinated or take medications, you’ve likely benefited from it.

Who’s looking out for the welfare of lab animals?

The regulatory framework surrounding animal research is a tangled web of acronyms, committees, and working groups. Since the Animal Welfare Act was passed in 1966, the USDA has been in charge of enforcing it through inspections and annual reports.

In theory, researchers have to justify the use of animals in their work. To conduct an animal experiment, scientists in the US go through a review process with their Institutional Animal Care and Use Committee (IACUC), which decides whether animals are “necessary” and whether steps are being taken to minimize their pain.

IACUCs are mostly comprised of researchers who experiment on animals and the veterinarians who help them, strongly biasing committees toward approving animal experiments. In the US and elsewhere, scientists are subtly incentivized to use animals, even when they aren’t actually necessary. Academic journals tend to preferentially publish work with animal methods , and academic careers hinge on accumulating publications . These norms seep into the labs where animal experiments are performed. New animal researchers often receive explicit instructions on how to steer clear of animal rights activists, according to several researchers I spoke with while working as a neuroscientist (as well as my own experience).

This can make holding institutions accountable for animal welfare violations challenging. While researchers are required to report information about animals in their facilities, like what medical procedures they’ve received and when they’ve been fed, they are told to keep these reports “ minimal, but complete .” In other words: Avoid including photos, videos, or graphic descriptions that could enrage activists or entice the media.

There also isn’t a clear legal definition for “animal cruelty” in research settings beyond violations of the basic standards outlined by the Animal Welfare Act. This leaves some room for interpretation about what is acceptable and what would constitute illegal treatment. The EU’s Directive 2010/63/EU , its equivalent of the Animal Welfare Act, emphasizes that animals should only be used if there are no other options and if the potential benefits of the research outweigh the animals’ suffering.

This cost-benefit analysis is subjective. For example, a team of immunologists studying cancer in mice would probably say that the potential public health benefits of their work justify harming mice. A team of science policy experts at PETA would say that mice aren’t ours to use and that these experiments often don’t translate to human trials, anyway .

To bridge this ethical divide, research universities and private companies in the UK have signed a Concordat on Openness on Animal Research , pledging to proactively and transparently inform the public about their treatment of lab animals. In the decade since its launch, nine other countries have followed suit. It’s likely not a coincidence that these countries generally have the tightest restrictions on animal use. However, an independent review found that Concordat signatories in the UK are still struggling to be transparent about their animal research practices in the face of potential disapproval.

On top of the slow pace for necessary regulation, stigma obscures the true nature of what happens in these labs. In the late 2000s, the most extreme opponents of animal testing used violence to try to end the practice, sending poisoned razors and death threats to lab heads and, in at least one case, firebombing a neurobiologist’s car . But rather than encourage scientists to reconsider their methods, attacks like these cemented a culture of silence. While physical violence is not representative of activism against animal testing today — which usually centers around investigations , government advocacy , and direct care for animals and has shifted to become more inclusive — the threat of retaliation still haunts animal researchers , some of whom are encouraged by their institutions to hide their connections to animal testing from the public.

Scientists “don’t want to feel like they’re bad people,” said neuroscientist and author Garet Lahvis, who has written about primate research for Vox.

What if I want to avoid animal testing altogether? What does “cruelty-free” mean?

After learning about what lab animals go through, some people will want to find ways to avoid the products of animal testing. This is much easier said than done, however.

Animal testing is pervasive in health care. Many treatments we take for granted today, like anesthesia , flu shots , and allergy medications , went through preclinical trials in animals before reaching us. They are also valuable to your health, so please keep taking your medicine if you need it. We have more power to avoid animal testing elsewhere. Animal testing requirements are generally looser to nonexistent for cosmetics, cleaning supplies, and other household chemicals, so it’s possible to buy “cruelty-free” makeup or laundry detergent.

The legal distinction between “cosmetics” and “drugs” is blurry, though. Essentially, drugs claim to affect the body’s structure or function in some way, while cosmetics are things you apply to your body to change your appearance (like lipstick) or clean yourself (like deodorant — but not soap, which is neither a cosmetic nor a drug, but its own special category ). Many products we might think of as cosmetics are, in fact, also drugs, like anti-dandruff shampoo, tinted moisturizer with sunscreen, and other cosmetics that claim to treat some ailment. In the US, all of these items had to be tested on animals until the FDA Modernization Act 2.0 took effect in 2023 .

Cruelty-free claims used on product labels are often misleading, and differences in regulation across countries add to the confusion.

For years, the EU , Canada, Mexico, and 16 other countries (including South Korea, for the skincare girlies ) have had legislation in place banning animal testing for cosmetics or their ingredients (although last year, the UK changed their policy to allow testing for makeup ingredients again). But testing on final products or their ingredients has never been banned in the US. Even if a company doesn’t test its final product on animals, it may still run animal tests on raw ingredients. And even if those raw ingredients aren’t currently being tested on animals, they probably were when they were first introduced.

The US government doesn’t have a legal definition for the terms “cruelty-free” or “not tested on animals.” A product labeled “cruelty-free” likely earned voluntary certification from a private organization like Leaping Bunny or PETA’s Beauty Without Bunnies program by pledging to end animal testing at all stages of product development. The definition of “cruelty-free” isn’t standardized across animal protection groups, but earning a “bunny label” generally means that a brand attested to never conducting tests on animals during a product’s development.

Despite pressure from advocates and consumers, many US companies don’t bother with these pledges on animal testing. As of this year, approximately 310 brands globally still test their beauty and household cleaning products on animals. And some actively say they don’t test on animals at all but still sell their products to countries like China, which, until recently, required that all cosmetics (even imported ones) be tested on animals . Most certification programs exclude brands and products sold in China for this very reason.

To make it easier for US companies to sell truly cruelty-free products in China, US regulators and animal welfare advocates have been lobbying their Chinese counterparts for years to change their approach to animal testing for consumer products. Twenty years ago, Thomas Hartung, a toxicologist at the Johns Hopkins Center for Alternatives to Animal Testing, spoke with the National Medical Products Administration (China’s FDA) about regulating animal testing of chemicals and told me “it was like we were coming from Mars.”

In response to yearslong campaigns by organizations like PETA and the Institute for In Vitro Sciences, China recently lifted this requirement . It is now possible to buy Chinese cosmetics that weren’t tested on animals — kind of.

As of January 2021, China no longer requires pre-market or post-market animal testing for cosmetics, meaning that companies from the US and elsewhere can sell things like eyeliner or nail polish in China while still maintaining “cruelty-free” status. But certain “special cosmetics,” like sunscreen, teeth whiteners, and hair dye, or products made for children, are all still required to undergo animal testing. And if a product uses a raw ingredient that isn’t already approved in China, foreign companies have to either reformulate or get that ingredient approved, which requires more animal testing. So, it’s possible to sell US-made “cruelty-free” products in China, but it requires sifting through a confusing and ever-evolving swamp of documentation requirements.

We have made imperfect progress toward a world of cruelty-free cosmetics. While the number of animals used for cosmetic testing in the US has dropped by 90 percent since the 1980s, 44 of the largest 50 cosmetic brands in the world still are not cruelty-free . And without a consensus agreement on what “cruelty-free” actually means, consumers are left to guess which bunny labels are genuine and which are false advertising.

Since many brands can just slap on cruelty-free claims while still sending products abroad to animal testing labs, for now, if you want to avoid animal testing, Leaping Bunny and Beauty Without Bunnies are your best bets. These certifications consider post-market animal testing in other countries as part of their standards.

Alternative methods are (slowly) coming

In some places, like the UK, strict restrictions on animal research and a commitment to transparency have considerably improved lab conditions in recent decades. Companies like Neuralink , however, continue to perform high-risk, ethically dubious experiments hidden from the public eye.

While new alternative methods are under development, animal testing remains necessary in at least some circumstances. Tight regulation — and buy-in from scientists — will be key to minimizing harm in the meantime.

Nicole Kleinstreuer, acting director of the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) , told me that improving the current state of animal testing hinges on researchers gathering “the courage to admit that we can substantially improve upon how we’ve been doing things historically.”

Until relatively recently, alternatives to animal testing in many areas of science were very limited. But in the past decade, bioengineering and computer science have advanced rapidly. New tools like AI, organoids (balls of stem cells that grow into organ tissue), and CRISPR have made replacing animals, at least in certain experiments, more attainable.

For chemical testing, good animal-free research methods have been around for decades — long before most scientists considered using them. Even when well-validated animal alternatives exist, researchers can be slow to adopt them . Hartung, a toxicologist, said, “I turned 60 last year. The methods they’re using were introduced when I was in kindergarten.”

In 2007, the National Academies of Sciences, Engineering, and Medicine , a nonprofit that produces independent policy guidance for the US, laid out a strategy for researchers to move away from using animals in toxicity testing and to develop faster, more human-relevant models to take their place. Today, a number of working groups, both within the US and collaborating internationally, are still trying to put this principle into practice.

As the largest single public funder of biomedical research in the world, the National Institutes of Health (NIH) is uniquely positioned to influence animal testing. In 2023, the NIH spent an estimated $19 billion on US-based projects involving animals, according to Citizens for Alternatives to Animal Research and Experimentation. Between 2011 and 2021, they spent $2.2 billion on projects based in other countries — where oversight boils down to trusting self-generated, non-validated reports from foreign institutions.

Kleinstreuer said that changing the current state of animal research “really necessitates a sea change, and a dramatic investment on the part of funders, particularly the NIH.”

The people in charge of the money have the power to redistribute it and could choose to spend more of it on projects that don’t use animals and less on those that do. That’s the easy part. “It’s kind of the lowest-hanging fruit, and the easiest ask,” said Emily Trunnell , director of Science Advancement and Outreach at PETA. “Even people who are in support of animal testing are on board with the funding of different methods as well.”

NICEATM, led by Kleinstreuer, is doing the in-the-weeds work of figuring out how we’d know whether a replacement method is good enough to substitute for animal experiments. Earlier this year, the NIH also approved the Complement Animal Research in Experimentation (Complement-ARIE) Program , which will set up technology development centers for researchers to make better human-based models.

Non-animal methods can already outperform certain animal tests. Back in 2018, Hartung’s research group created algorithms mapping the relationships between 10,000 known chemical compounds. With this model and lots of data, they predicted the toxicity of 89 percent of the 48,000 toxic chemicals more accurately than animal tests could and for much less money — without endangering any living creatures. Since then, Hartung said things have only become better. But AI-driven research methods are still limited by what real-world data has already been collected. “When you have no data,” he said, “nothing is possible.”

In some cases, using animals is simply bad science. There are some questions “that absolutely necessitate a human cell-based approach,” Kleinstreuer said. “You can’t look at the efficacy of a drug whose target is not expressed in animals by using animal models,” she added. Certain cancer drugs target protein receptors that only exist in humans, and gene therapies often aim to rewrite human-specific DNA sequences. One emerging option: take a sample of human cells, reprogram them to behave like whatever cells you want them to be, and test your drug on the resulting tissue sample.

These tools offer exciting opportunities to personalize medicine to individual patients, but it’s still tough to extrapolate results from a small mass of lab-grown cells in a tightly controlled environment to a human body and the complex interactions of its organ systems. Cancer and embryonic development are incredibly complex biological processes, involving lots of different interconnected body parts that evolve over time. Without that capability, Kleinstreuer said it’s harder to argue that a substance is actually safe and ready to clear for human use.

Change happens one retirement at a time

As it stands, alternatives to animal tests are not being used as widely as they should be, especially in cosmetics. But if we want to study things like deep brain stimulation or run safety tests on new cancer drugs , animal tests are all we have.

While we are stuck with animal experiments, we can try to limit them and make them more humane. Lahvis believes that we should have extremely strict criteria for what animal experiments are funded. Strategically allocating grant funding could not only save millions of lives, but also inspire better science.

Convincing animal researchers to replace animals with other methods is still a huge challenge. Hartung joked that in academia, change happens “one retirement at a time.” Unfortunately, “it’s often been one graveyard at a time,” as retired scientists continue to serve as reviewers who help choose what new projects get funded and published.

The further along a scientist is in their career, the more challenging it becomes to pivot. Because scientists are pushed to maintain a constant level of productivity, Trunnell said, someone who builds their whole lab around their current use of animal models has no incentive to change, unless they have a strong desire to do so. Changing tactics could mean putting their job on the line.

“We’re highly leveraged by the system to keep doing what we’ve always done,” Lahvis agreed. And, Hartung said, turning against a tried-and-true method would require a scientist invalidating their existing body of work or at least acknowledging that it was either unethical, ineffective, or inefficient. Using past observations to inform future experiments is at the core of the scientific method, but, Hartung said, “We’re not trained to be very self-critical.”

That said, a growing number of scientists support the development of non-animal methods, even as they continue to work with animals themselves. People want new tools, whether for the sake of animal welfare or simply because it would make for better science. We might just have to wait another generation.

• Animal Welfare

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Modern (1940’s-present)

105 Animal Testing

Elizabeth Mey and Nicolette Occhifinto

Introduction

Animal testing is experiments on live, nonhuman animals to assess the effectiveness or safety of cosmetics, household products, or medicines. The earliest sign of animal testing dates back to 500 BCE, but it gained noticeable attention in the 19th and 20th centuries with the rise of biomedical research. This chapter will explore how animal testing relates to science and technology in society while defining various types of animal testing.

Connection to STS

STS is a field that examines the social, cultural, political, and ethical dimensions of science and technology. Animal testing relates to STS as the relationship between science, technology, and society explores the use of animals in research. STS allows the question of ethics, and animal testing causes questions regarding the ethical aspect of the treatment of animals and societal values. STS also gets involved when it comes to the development of alternative methods of animal testing.

Exploring other factors, such as social and cultural, open up communication and acceptance of alternative technology and techniques within the scientific community. Animal testing also varies across different countries and cultures. STS provides an outlet that allows others to understand how cultural differences influence attitudes toward animal testing and the development of policies. STS allows people to explore the controversial differences between societal values, ethical considerations, and scientific practices, which allows more of a comprehensive understanding of the overall implications of this topic.

Types of animal testing

Animal testing, a practice ingrained in scientific research and product development, involves subjecting animals to various experiments to evaluate the safety and efficacy of different substances and procedures. From pharmaceutical trials to toxicity assessments and cosmetic testing, the ethical implications of such practices have sparked widespread debate. The ongoing discussion reflects the complexity of balancing scientific progress with ethical considerations with animal experimentation.

Pharmaceutical Testing

Animals, such as rats, are used to test the efficiency of a new drug before it advances to human clinical trials. This testing involves studying the drug’s effect on metabolism, organ systems, and overall health.

Genetic Research

Animals can be genetically modified or manipulated to study specific genes and their functions. It can help scientists understand genetic disorders, develop gene therapies, or investigate the role of genes in various biological processes.

Behavioral Studies

Animals are used in behavioral research to study learning, memory, cognition, and other aspects. These studies involve various setups, such as mazes and observational techniques.

Biomedical Research

Animals are used in biomedical research to understand the biological process, study diseases, and develop new medical treatments. For example, in the discipline of genetic engineering, mice are used as “transgenic animals.” These organisms are permanently altered by the addition of a foreign DNA sequence to its genome. A genome is the complete set of genetic information in an organism. These transgenic animals are used to study the function of human genes. The mouse below was injected with the human gene for obesity.

Animal testing within the cosmetics industry

Animal testing has long been a controversial practice within the cosmetics industry, with various ethical and scientific concerns surrounding its use. Traditionally, animals like rabbits, mice, rats, and guinea pigs have been subjected to tests to evaluate the safety and efficacy of cosmetic products. These tests often involve applying substances to the animals’ skin or eyes, force-feeding them chemicals, or even inhaling substances to assess potential toxicity. Such practices have sparked significant public outcry and have led to calls for more humane and alternative testing methods.

Despite advancements in technology and increasing societal pressure, animal testing still persists in certain parts of the cosmetics industry. Well known brands such as Estee Lauder, Benefit, and dozens of subsidiary brands are some of the largest contributors. A brand like Estee Lauder generates around $15.15 billion in revenue per year, making it difficult for animal testing practices to change given their financial success.

However, there has been a growing trend towards phasing out animal testing in the cosmetics industry, driven by consumer demand for cruelty-free products and advancements in alternative testing methods. This rising trend, popularized amongst the younger generations by social media, has resulted in many new brands entering the market with high quality, cruelty free products. Rare Beauty, a cruelty free cosmetics brand owned by singer Selena Gomez, has skyrocketed in success over the past 5 years. Starting from nothing, the brand has been hugely successful with authentic campaigns that are focused on quality and authenticity of product sourcing. In 2024, Rare Beauty is projected to gross $300 million. This is just one example of the power of branding and imagery in how animal testing can be leveraged effectively in society today.

international impact on the cosmetic industry

One of the key hurdles in addressing animal testing internationally is the lack of harmonization among regulatory agencies across different countries and regions. While some jurisdictions have made significant progress in phasing out animal testing, others still require it as a regulatory requirement for cosmetic products to be sold. This lack of uniformity complicates efforts to adopt alternative testing methods on a global scale and restricts the ability of companies to standardize their practices across markets. This is another hurdle for multinational companies to overcome.

Moreover, cultural norms and attitudes towards animal welfare vary widely around the world, further complicating efforts to eliminate animal testing in the cosmetics industry internationally. In some regions, there may be less public awareness or concern about the ethical implications of animal testing, making it challenging to gather support for legislative changes or industry-wide initiatives. Bridging these cultural differences and fostering international collaboration will be crucial in overcoming the challenges associated with animal testing and advancing towards a more humane and sustainable cosmetics industry on a global scale.

Animal testing and missing voices

When discussing controversial topics such as animal testing, it is imperative to consider various perspectives and acknowledge the diverse range of voices involved in the conversation. Missing voices are the absence or underrepresentation of views, experiences, and opinions. It highlights the need for a more inclusive and diverse representation of voices to ensure a comprehensive and equitable understanding of issues.

Scientists and researchers- scientists and researchers use animal models in their work and even work on developing alternative methods that do not involve animals. The goal is to refine, reduce, and replace the use of animals in research to improve the ethical and scientific aspects of experimentation. Alternative testing method advocates- organizations and individuals promote developing and adopting alternative testing such as computer modeling and in vitro studies. These methods aim to reduce or replace the use of animals in research.

The field of STS plays a crucial role in examining the complex relationships involved in animal testing. The missing voices provide perspectives contributing to the broader understanding of animal testing and alternative methods. Animal testing is a complicated debate. The various types of experimentation include pharmaceutical testing, genetic research, behavioral studies, etc. As technological advancements continue to shape research methodologies, there is a pressing need for a more inclusive dialogue that integrates the perspectives of various stakeholders, including ethicists, scientists, policymakers, and advocates for animal welfare. Recognizing and addressing the concerns of missing voices, such as those of the animals involved and communities affected, is essential for creating an inclusive approach to scientific inquiry. Moving forward, an ethical and sustainable future in research requires an ongoing commitment to exploring alternative testing methods, promoting transparency, and engaging in open conversations that prioritize the well-being of all stakeholders.

AI Use Disclosure

I Used ChatGPT to help find information about animal testing and organize the chapter appropriately.

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ALTEX – Alternatives to Animal Experimentation,26 (1), 3–16. https://doi.org/10.14573/altex.2009.1.3

Companies That Do Test on Animals. PETA. https://crueltyfree.peta.org/companies-do-test/

Kabene, S., & Baadel, S. (2019). Bioethics: a Look at Animal Testing in Medicine and Cosmetics in the UK.

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Kim, H. (2021, November 12).Makeup Testing on Animals: Know the Brands That Do and Don’t. Sentient Media.  C

Knopp, J. (2022). What Is Animal Testing and Which Animals Are Used for Testing?” Thehumaneleague. Thehumaneleague.Org.

Liebsch, M., Grune, B., Seiler, A., Butzke, D., Oelgeschläger, M., Pirow, R., Adler, S., Riebeling, C., & Luch, A. (2011a, May 24). Alternatives to animal testing: Current status and future perspectives – archives of toxicology. SpringerLink. https://link.springer.com/article/10.1007/00204-011-0718-x 

Davies, G., Gorman, R., & Crudgington, B. (2020). Which patient takes centre stage? Placing patient voices in animal research. In GeoHumanities and Health (pp. 141–155). doi:10.1007/978-3-030-21406-7_9

Laybourne, A. (2023). Animal Testing Facts- Why Should Animal Experimentation Be Stopped?” Wold Animal Foundation. In worldanimalfoundation.org/advocate/animal-testing-facts/#:~:text=areas in Which Animal Testing Occurs 1 Cosmetics.

Kiani, A. K., Pheby, D., Henehan, G., Brown, R., Sieving, P., Sykora, P., … INTERNATIONAL BIOETHICS STUDY GROUP. (2022). Ethical considerations regarding animal experimentation. Journal of Preventive Medicine and Hygiene, 63(2 Suppl 3), E255–E266. doi:10.15167/2421-4248/jpmh2022.63.2S3.2768

Swaters, D., van Veen, A., van Meurs, W., Turner, J. E., & Ritskes-Hoitinga, M. (2022). A history of regulatory animal testing: What can we learn? Alternatives to Laboratory Animals: ATLA, 50(5), 322–329. doi:10.1177/02611929221118001

Lu, C., Liu, X., Liu, J., Tang, X., Zhu, G., Striepen, B., & Suo, X. (2022). Immunocompetent rabbits infected with Cryptosporidium cuniculus as an animal model for anti-cryptosporidial drug testing. International Journal for Parasitology, 52(4), 205–210. doi:10.1016/j.ijpara.2021.10.006

Nature Publishing Group. (2014). Genome . Nature news. https://www.nature.com/scitable/definition/genome-43/#:~:text=A%20genome%20is%20the%20complete,molecules%20of%20DNA%20called%20chromosomes.

To the extent possible under law, Elizabeth Mey and Nicolette Occhifinto have waived all copyright and related or neighboring rights to Science Technology and Society a Student Led Exploration , except where otherwise noted.

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Some 115 million animals are used each year in scientific research, mainly in the US, Japan, China, Australia, France, Canada, the United Kingdom, Germany, Taiwan and Brazil, according to a 2005 estimate prepared by the British Union for the Abolition of Vivisection and the Dr. Hadwen Trust for Humane Research. Although other experts question this figure, the fact is that global science continues to depend to a large extent on animal experimentation , a practice that is rejected among certain sectors of society.

In this series of questions and answers we summarize the current state of animal experimentation and examine its future prospects.

What is vivisection? Is it still practiced?

Vivisection is the dissection of live animals for research purposes, originally without anaesthesia when it did not yet exist. In animals it has been used extensively throughout history, giving rise to macabre stories such as the vivisection of a dog carried out by the English polymath Robert Hooke in the seventeenth century to study the functioning of the lungs, which horrified the scientist himself.

In the 19th century, a movement against vivisection began, which led to the enactment in the United Kingdom of the first laws against cruelty to animals. The 1876 version required for the first time the use of anaesthesia in experiments.

Nowadays, the term “vivisection” is not often used in the scientific field and is rarely practiced in its original sense, but activist organizations usually apply it to all experimentation with animals , even with the use of anaesthesia or non-invasive techniques.

continue to be practiced, subject to generalized criteria to minimize the pain and stress. One example is optogenetics , the technique of implanting a fibre optic cable in the brain to stimulate neurons with light . The procedure is not painful for animals and scientists see optogenetics as a fundamental tool for the study of neurological diseases.

What positions do different countries have regarding animal experimentation?

Most developed countries have legislation that seeks to minimize the use of laboratory animals and to limit the pain inflicted on them.

The European Union is governed by Directive 2010/63/EU , adopted into the legislation of each member state and in force since 2013. This European regulation, considered one of the strictest in the world, covers all vertebrates, including their foetal stages in the last third of their development, in addition to the cephalopods. It establishes standards for the care of animals and the facilities involved, which are subject to periodic inspections . In addition, it regulates the evaluation of each proposal to authorize the use of animals and it promotes the research and application of alternatives to animal experimentation.

Perhaps the most demanding regulation in the world is the British one. The Animals (Scientific Procedures) Act of 1986, revised in 2013, requires a cost-benefit analysis as a requirement to authorize animal experiments—something that is also covered by German law—as well as customizing the licenses for researchers and technicians who perform these tests. In the USA, the only relevant federal law is the Animal Welfare Act (AWA) of 1966, which suffers from a serious lack of exclusion for mice and laboratory rats, the animals most used in experimentation, also leaving out birds and fish. According to the bioethics research institute The Hastings Center, this means that the AWA does not cover 95% of the animals used in the laboratories, although these species are covered by other non-federal regulations.

Other countries such as Australia or Brazil also have regulations on the issue. In Canada it is the responsibility of the provincial governments. In Japan, in 2011, a local entity claimed that there was poor compliance with the relevant legal directives. In 2006, China adopted the first comprehensive legislation on the welfare of laboratory animals at the national level, which is complemented by other local and institutional guidelines.

Are cosmetics still being tested on animals?

The popular rejection of the testing of cosmetics on animals has led to changes in the regulations and the stances adopted by some companies. The United Kingdom pioneered the introduction in 1998 of the first legislation that prohibited the testing of cosmetics on animals. In 2013, EU regulations came into force that make these tests illegal, as well as the commercialization of cosmetic products that have been tested on animals . India, Israel, Norway and Switzerland have passed similar laws, while the US and Japan still allow these tests.

One notable case is that of China, which has traditionally required that all cosmetics for sale in the country be tested on animals, which has led many companies in the sector to continue using these practices to access the Chinese market. Since 2014, China has begun to vary its course by introducing certain exemptions, but animal testing is still mandatory for cosmetics manufactured in other countries that are sold in China in physical stores.

Is it possible to do away with animal experimentation?

In 1959, the zoologist William M. S. Russell and the microbiologist Rex L. Burch introduced the concept of the Three Rs (3Rs): Replacement, Reduction and Refinement , the principles that attempt to guide the ethical course of animal experimentation until its eventual disappearance. The current legislation of many countries on animal testing includes references to the 3Rs as the path to follow. For example, reference laboratories for the investigation of alternatives have been established in the EU.

In the case of cosmetics, animal testing has been replaced by tests employing cell cultures, artificial human skin and organ models. In scientific research, there is an attempt to use in vitro systems, biochips and mathematical simulation models. Many scientists support the 3R pathway, but believe that “it is unrealistic to expect this to be possible in every area of ​​scientific research in the immediate future,” according to the Research Defence Society (now called Understanding Animal Research). A 2015 survey by the Pew Research Center in the US revealed that 89% of scientists are in favour of animal experimentation because it is still irreplaceable.

Perhaps the most obvious example of this is preclinical drug trials, where drugs are tested on animals before studies on patients are begun. Currently, it is still impossible to provide in vitro systems or computer models capable of simulating all the complexity of an organism and all the potential effects of a new medication.

Javier Yanes

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Frequently Asked Questions

Why use animals in research?

Animal research is essential for three basic purposes:

• To explore basic biology
• To develop treatments for diseases and disabilities
• To promote health and safety for animals, people and the environment

Why can’t you replace animals with a computer?

Humans, like all animals, are extremely complicated. Drug development, for example, shows the difficulty of finding an accurate alternative. Many drugs are discovered because a chemical compound does something useful in a laboratory dish, but that discovery is followed by a long process of trial and error: first with simple animals, then with more advanced ones. Even the drugs that do reach human trial often either fail to work or have unacceptable side effects, often discovered first through testing on animals.

It’s true that some drugs and diseases “work” one way in mice and another in people; but if animal research can be misleading, computer-based research is likely to be even more difficult. When so much is unknown, how could we possibly program a computer to test drugs and procedures? To put it another way: we will not be able to do all our health and biology research in computers until we have nothing left to learn about health and biology.

Do your researchers look at alternatives to using live animals?

Yes. Following the federal Animal Welfare Act, the UW–Madison Researcher’s Guide to Animal Care and Use specifies that investigators consider alternatives to animal use, as part of its commitment to humane research:

• Replacement; using non-animal alternatives, such as cell culture, or choosing a species lower on the phylogenetic tree (mice instead of monkeys)
• Reduction; using the smallest number of animals necessary for valid scientific results
• Refinement; choosing procedures that minimize pain and distress.

Can you reduce your use of animals by doing something else?

Yes, and we are. For example, two types of stem cells (embryonic and induced pluripotent) are producing human cells that are already being used to test candidate drugs for toxicity. These stem cells are routinely used to produce human heart muscle cells, and because heart toxicity can be lethal, this process will save the lives of both animals and people. Other projects are looking into computer simulations of various sorts that can help reduce the need for research animals.

The federal government is looking into alternatives to animal research .

Who regulates animal research on campus?

Both federal and university bodies regulate research using vertebrate animals:

• U.S. Department of Agriculture .
• Office of Laboratory Animal Welfare, National Institutes of Health .
• Food and Drug Administration .
• Animal research at UW–Madison is overseen by five animal care and use committees, with assistance from the Research Animal Resources Center .

How is an animal research proposal approved?

Animal research is described and governed by a “protocol,” a description of the project that constitutes a contract between the principal investigator and the UW–Madison Animal Care and Use Committee (ACUC).

The review and approval for an animal care and use protocol follows these steps:

• Protocol application is prepared by the investigator and submitted to the Research Animal Resource Center (RARC), which assigns the protocol to the appropriate Animal Care and Use Committee for review.
• The ACUC can approve the protocol as is, approve it pending answers to certain questions, or require substantial revision.
• RARC staff communicates the ACUC’s approval or request for further information/revision to the Investigator.
• Research can begin after the protocol is approved.

Prior to making any significant change to the protocol, investigators must get approval of the relevant ACUC.

Who uses animals in research on campus?

A wide variety of UW–Madison researchers, including veterinarians, medical doctors, scientists and students at all levels of the university, are involved in animal research. Everybody involved in animal research must be trained in animal regulations and care, and have the necessary skills and training. Also, the research must be carried out in licensed premises meeting strict standards and subject to regular inspection.

Is it ethical for humans to experiment on animals?

The wide range of students, faculty and scientists at UW–Madison who use animals in research believe that the use of animals in medical research is ethical when performed under strict regulation, in situations where practical alternatives do not exist. The ethical decision amounts to a trade-off between the harm that may be done to the animals and the benefits to suffering patients, today and in the future. The vast majority of biomedical scientists believe that the abolition of animal research is an unrealistic position.

While we respect the viewpoint of those who oppose research on animals, we feel that the potential benefits to human welfare, animal welfare and basic knowledge about life are too important to not do the research. An argument can be made that refraining from this research would actually be unethical.

Do research animals ever get adopted?

The University of Wisconsin–Madison has a long-standing policy on research animal adoption. It allows UW–Madison to put animals up for adoption with the approval of the university’s veterinarians and after consideration of a number of factors. These are addressed in the institution’s full policy, which can be found here: https://www.rarc.wisc.edu/iacuc/acapac/2012-049-v_laboratory_and_teaching_animal_adoption.html

To be eligible for adoption, animals must no longer be needed by the university for research or teaching. Animals must also be healthy and must have a suitable temperament and long-term health status to be a pet, as determined by university research animal veterinary staff.

UW–Madison policy does not permit adoption of nonhuman primates. With few exceptions, this is primarily because the animals continue to be needed for research. The national primate centers funded by the National Institutes of Health maintain stable animal colonies that are studied across the lifespan. Health research at these centers includes studies of aging and diseases associated with age, such as Alzheimer’s disease and cognitive decline. Thus, older animals contribute to scientific studies.

The centers also maintain valuable tissues and cells from animals that are humanely euthanized. Those tissues are critical to a wide range of scientific studies and are shared with scientists around the world. This helps answer important scientific questions about human and animal health, but also likely reduces — through collaboration and sharing — the overall number of non-human primates in research.

UW–Madison may consider retirement of non-human primates only in the event they are no longer needed for research, only if the facilities receiving them can assure high-quality care, and only to facilities with a demonstrated ability to protect the animal’s wellbeing and health by providing stable care over the course of its lifetime. Any such facilities would necessarily be subject to regulation and monitoring by the United States Department of Agriculture on a permanent basis.

Animal Research

Top 10 animal research faqs.

Although animals are an essential part of biomedical research, you may have some questions about which animals are involved, the roles they play, and the care they receive.

Here we answer some common questions. If you don’t find the answer to your question, please email it to us.

1. How do we learn from biomedical research using animals?

Each species in the animal kingdom is unique, but there are similarities as well as differences between species. Researchers usually study animal models that are biologically similar to humans, although they also look at differences. This approach is called comparative medicine.

Pigs and humans have similar skin and cardiovascular systems. By studying pigs, researchers can learn more about skin conditions and heart problems and find better ways to treat them.

Organisms that look very different can be very similar genetically.

The differences between species can also provide great insights. Sharks rarely get cancer, cockroaches can regenerate damaged nerves, some amphibians can regrow lost limbs, and zebrafish can regenerate damaged heart muscle. By studying these animals we may learn how their bodies accomplish these remarkable feats and then apply the same principles to human medicine.

Organisms that look very different can be very similar genetically. To study genetic disorders such as Down Syndrome or Parkinson’s Disease, researchers might study a mouse model which shares 94% of its DNA with humans. Zebrafish have 75 – 80% of the same DNA as humans, and even bananas share 50%. (Each of these estimates is based on certain assumptions so they may vary depending on how the calculation was made.)

2. Who cares for animals in research?

An important but little-known fact about biomedical research is that in addition to the scientists who conduct the research, every research institution also has veterinarians, husbandry specialists and animal care technicians. These are dedicated professionals whose job is to ensure that laboratory animals receive the highest quality of care. They also work together to minimize discomfort or distress because these affect not only the well-being of animals, but also the reliability of the research itself.

Most research animals do not experience procedures that are any more invasive than what most people face during an annual physical examination. When potentially uncomfortable procedures are involved, anesthetics and analgesics are used to relieve discomfort.

Regulatory laws and guidelines, such as those listed in the U.S. Animal Welfare Act (AWA), which excludes rats, mice and birds, and in the Public Health Service (PHS) Policy , which covers all vertebrate animals in federally-funded research, mandate high-quality nutrition, housing and veterinary care for research animals.

Research institutions are required to have an Institutional Animal Care and Use Committee (IACUC).  IACUCs approve and review research protocols, ensure that anesthesia and postoperative medications are used when appropriate, and that alternatives to animals are sought out and integrated into studies whenever possible.

Most institutions go above and beyond regulatory requirements by volunteering to have their programs reviewed every three years by AAALAC International . This accreditation process is very stringent and institutions with AAALAC accreditation are known for their commitment to excellence and humane animal care.

3. How do laboratory animal science professionals feel about their work?

Laboratory animal science professionals know that animal-based research leads to treatments and cures for both people and animals. They are very passionate about their work. By caring for and working with animals in research, they provide hope for you and your loved ones, including your pets.

It’s estimated that rodents and fish comprise well over 95% of all animals used in research.

4. What happens to the animals?

Some research questions can only be answered by harvesting the organ or tissue of interest and examining it at the microscopic and molecular level and animals must be euthanized for this reason. The American Veterinary Medical Association (AVMA) Guidelines on Euthanasia ensure that euthanasia is performed humanely. Several research institutions have adoption programs for animals in studies that do not require euthanasia.

5. Why are there increasing numbers of mice, rats and fish used in research?

It’s estimated that rodents and fish comprise well over 95% of all animals used in research. The number of mice, rats and zebrafish involved due to the ongoing development of genetic research tools. These methods allow researchers to modify the genome in animals to model common diseases in order to study potential cures.

For example, scientists have been able to insert the human genes responsible for a type of Alzheimer’s disease into rodents, resulting in the rodents developing the cognitive dysfunction and memory loss that people experience.

6. Why can’t alternatives like computers replace research animals?

In many cases they have, but while computers provide terrific resources for researchers all over the world, they do have limitations. For instance, computers are only able to provide information or models of known phenomena.  Because research consistently seeks answers to unknowns, a computer is unable to simulate how a particular cell might interact or react with a medical compound, or how a complex biological system such as the circulatory system will react to a new drug directed to improve organ function.

A single living cell is many times more complex than even the most sophisticated computer program. There are an estimated 50 -100 trillion cells in the human body, all of which communicate and interact using a complicated biochemical language –  a language researchers have only just begun to learn. Studies using isolated cells or tissues almost always precede animal-based research, but researchers must study whole living systems to understand the effectiveness of treatments and, their potential benefits and dangers.

U.S. law requires that all new drugs, medical devices and procedures first be evaluated in animals for safety and efficacy before clinical (human) trials can begin.

7. What is our moral obligation?

Pain and suffering matter whether experienced by animals or humans. Researchers seek to relieve suffering in both humans and animals by enhancing our ability to prevent, diagnose, and treat disease. They use many different approaches, including computers modeling, cellular and molecular studies, tissue cultures, gene sequencing, epidemiology, and whole animals. Animal studies are but one building block in our research efforts, but they are a vital one.

Not only humans, but also animals – pets, livestock and wildlife – benefit from animal-based research. Discoveries such as antibiotics, anesthetics, surgical techniques, and diagnostic imaging were developed through animal studies and have also enhanced the lives of other animals by improving veterinary care.

When answering a research question requires animal studies, laboratory animal care professionals seek to minimize the pain and distress of their charges by providing them with clean, enriched environments, proper nutrition, and specialized veterinary care.

It also is worth noting that discoveries such as antibiotics, anesthetics, surgical techniques, and diagnostic imaging developed through animal studies and have improved the lives of other animals by improving veterinary care.

8. Are researchers in it for the money?

Doctors, scientists and laboratory animal care professionals are involved in research because they recognize the limitations in our current ability to prevent, diagnose, and cure disease in humans and animals. Biomedical research is a noble profession. Many in the field could make more money following other career paths.

Animal-based research is extremely expensive and it requires a tremendous investment in well-trained people and special facilities. It is also heavily regulated: an institution must spend a significant amount of time and money to ensure that all applicable regulations and guidelines are met. Conducting animal-based research is not something that institutions undertake without a great deal of deliberation and preparation.

9. Why are animals needed to screen consumer products for safety when products tested by alternative methods, (so-called ‘cruelty free’ items), are available?

The law requires that all new chemical compounds be screened for safety using a living system.

It is important to understand what “cruelty free” labels really mean. By definition anyone can use “cruelty free” labels if:

• As the distributing manufacturer they have not directly evaluated the product in animals. A company can still use the “cruelty-free” label if they send their product to another company for screening in animals.
• Some (but not all) components of the product have been screened with animals.  In some cases, products that have been previously evaluated and found safe may be used by other companies and marketed as “cruelty free.” For example, if compound A was safe for animals and compound B was also safe, companies can combine compound A and B into compound C and, without further screening with animals, sell it labeled as “cruelty free” and “not tested on animals.”

10. How can we be sure lost or stolen pets are not used in research?

Pets do become lost and some may never be found but that does not mean that they end up in research laboratories. It is illegal to steal pets for research. In fact. the Animal Welfare Act , first passed in 1966, specifically states that it be enacted “in order to protect the owners of dogs and cats from theft of such pets.”  Over 99% of the animals used in today’s research are “purpose bred” (i.e., bred specifically for research purposes). Those not specifically created for research come from licensed Class B animal dealers that are regulated and inspected by the USDA.

FOR MORE ANIMAL RESEARCH FAQs, VISIT:

American Physiological Society

European Animal Research Association

Foundation for Biomedical Research

Pennsylvania Society for Biomedical Research

New Jersey Association for Biomedical Research

North Carolina Association for Biomedical Research

Understanding Animal Research (UK)

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The Flaws and Human Harms of Animal Experimentation

Nonhuman animal (“animal”) experimentation is typically defended by arguments that it is reliable, that animals provide sufficiently good models of human biology and diseases to yield relevant information, and that, consequently, its use provides major human health benefits. I demonstrate that a growing body of scientific literature critically assessing the validity of animal experimentation generally (and animal modeling specifically) raises important concerns about its reliability and predictive value for human outcomes and for understanding human physiology. The unreliability of animal experimentation across a wide range of areas undermines scientific arguments in favor of the practice. Additionally, I show how animal experimentation often significantly harms humans through misleading safety studies, potential abandonment of effective therapeutics, and direction of resources away from more effective testing methods. The resulting evidence suggests that the collective harms and costs to humans from animal experimentation outweigh potential benefits and that resources would be better invested in developing human-based testing methods.

Introduction

Annually, more than 115 million animals are used worldwide in experimentation or to supply the biomedical industry. 1 Nonhuman animal (hereafter “animal”) experimentation falls under two categories: basic (i.e., investigation of basic biology and human disease) and applied (i.e., drug research and development and toxicity and safety testing). Regardless of its categorization, animal experimentation is intended to inform human biology and health sciences and to promote the safety and efficacy of potential treatments. Despite its use of immense resources, the animal suffering involved, and its impact on human health, the question of animal experimentation’s efficacy has been subjected to little systematic scrutiny. 2

Although it is widely accepted that medicine should be evidence based , animal experimentation as a means of informing human health has generally not been held, in practice, to this standard. This fact makes it surprising that animal experimentation is typically viewed as the default and gold standard of preclinical testing and is generally supported without critical examination of its validity. A survey published in 2008 of anecdotal cases and statements given in support of animal experimentation demonstrates how it has not and could not be validated as a necessary step in biomedical research, and the survey casts doubt on its predictive value. 3 I show that animal experimentation is poorly predictive of human outcomes, 4 that it is unreliable across a wide category of disease areas, 5 and that existing literature demonstrates the unreliability of animal experimentation, thereby undermining scientific arguments in its favor. I further show that the collective harms that result from an unreliable practice tip the ethical scale of harms and benefits against continuation in much, if not all, of experimentation involving animals. 6

Problems of Successful Translation to Humans of Data from Animal Experimentation

Although the unreliability and limitations of animal experimentation have increasingly been acknowledged, there remains a general confidence within much of the biomedical community that they can be overcome. 7 However, three major conditions undermine this confidence and explain why animal experimentation, regardless of the disease category studied, fails to reliably inform human health: (1) the effects of the laboratory environment and other variables on study outcomes, (2) disparities between animal models of disease and human diseases, and (3) species differences in physiology and genetics. I argue for the critical importance of each of these conditions.

The Influence of Laboratory Procedures and Environments on Experimental Results

Laboratory procedures and conditions exert influences on animals’ physiology and behaviors that are difficult to control and that can ultimately impact research outcomes. Animals in laboratories are involuntarily placed in artificial environments, usually in windowless rooms, for the duration of their lives. Captivity and the common features of biomedical laboratories—such as artificial lighting, human-produced noises, and restricted housing environments—can prevent species-typical behaviors, causing distress and abnormal behaviors among animals. 8 Among the types of laboratory-generated distress is the phenomenon of contagious anxiety. 9 Cortisone levels rise in monkeys watching other monkeys being restrained for blood collection. 10 Blood pressure and heart rates elevate in rats watching other rats being decapitated. 11 Routine laboratory procedures, such as catching an animal and removing him or her from the cage, in addition to the experimental procedures, cause significant and prolonged elevations in animals’ stress markers. 12 These stress-related changes in physiological parameters caused by the laboratory procedures and environments can have significant effects on test results. 13 Stressed rats, for example, develop chronic inflammatory conditions and intestinal leakage, which add variables that can confound data. 14

A variety of conditions in the laboratory cause changes in neurochemistry, genetic expression, and nerve regeneration. 15 In one study, for example, mice were genetically altered to develop aortic defects. Yet, when the mice were housed in larger cages, those defects almost completely disappeared. 16 Providing further examples, typical noise levels in laboratories can damage blood vessels in animals, and even the type of flooring on which animals are tested in spinal cord injury experiments can affect whether a drug shows a benefit. 17

In order to control for potential confounders, some investigators have called for standardization of laboratory settings and procedures. 18 One notable effort was made by Crabbe et al. in their investigation of the potential confounding influences of the laboratory environment on six mouse behaviors that are commonly studied in neurobehavioral experiments. Despite their “extraordinary lengths to equate test apparatus, testing protocols, and all possible features of animal husbandry” across three laboratories, there were systematic differences in test results in these labs. 19 Additionally, different mouse strains varied markedly in all behavioral tests, and for some tests the magnitude of genetic differences depended on the specific testing laboratory. The results suggest that there are important influences of environmental conditions and procedures specific to individual laboratories that can be difficult—perhaps even impossible—to eliminate. These influences can confound research results and impede extrapolation to humans.

The Discordance between Human Diseases and Animal Models of Diseases

The lack of sufficient congruence between animal models and human diseases is another significant obstacle to translational reliability. Human diseases are typically artificially induced in animals, but the enormous difficulty of reproducing anything approaching the complexity of human diseases in animal models limits their usefulness. 20 Even if the design and conduct of an animal experiment are sound and standardized, the translation of its results to the clinic may fail because of disparities between the animal experimental model and the human condition. 21

Stroke research presents one salient example of the difficulties in modeling human diseases in animals. Stroke is relatively well understood in its underlying pathology. Yet accurately modeling the disease in animals has proven to be an exercise in futility. To address the inability to replicate human stroke in animals, many assert the need to use more standardized animal study design protocols. This includes the use of animals who represent both genders and wide age ranges, who have comorbidities and preexisting conditions that occur naturally in humans, and who are consequently given medications that are indicated for human patients. 22 In fact, a set of guidelines, named STAIR, was implemented by a stroke roundtable in 1999 (and updated in 2009) to standardize protocols, limit the discrepancies, and improve the applicability of animal stroke experiments to humans. 23 One of the most promising stroke treatments later to emerge was NXY-059, which proved effective in animal experiments. However, the drug failed in clinical trials, despite the fact that the set of animal experiments on this drug was considered the poster child for the new experimental standards. 24 Despite such vigorous efforts, the development of STAIR and other criteria has yet to make a recognizable impact in clinical translation. 25

Under closer scrutiny, it is not difficult to surmise why animal stroke experiments fail to successfully translate to humans even with new guidelines. Standard stroke medications will likely affect different species differently. There is little evidence to suggest that a female rat, dog, or monkey sufficiently reproduces the physiology of a human female. Perhaps most importantly, reproducing the preexisting conditions of stroke in animals proves just as difficult as reproducing stroke pathology and outcomes. For example, most animals don’t naturally develop significant atherosclerosis, a leading contributor to ischemic stroke. In order to reproduce the effects of atherosclerosis in animals, researchers clamp their blood vessels or artificially insert blood clots. These interventions, however, do not replicate the elaborate pathology of atherosclerosis and its underlying causes. Reproducing human diseases in animals requires reproducing the predisposing diseases, also a formidable challenge. The inability to reproduce the disease in animals so that it is congruent in relevant respects with human stroke has contributed to a high failure rate in drug development. More than 114 potential therapies initially tested in animals failed in human trials. 26

Further examples of repeated failures based on animal models include drug development in cancer, amyotrophic lateral sclerosis (ALS), traumatic brain injury (TBI), Alzheimer’s disease (AD), and inflammatory conditions. Animal cancer models in which tumors are artificially induced have been the basic translational model used to study key physiological and biochemical properties in cancer onset and propagation and to evaluate novel treatments. Nevertheless, significant limitations exist in the models’ ability to faithfully mirror the complex process of human carcinogenesis. 27 These limitations are evidenced by the high (among the highest of any disease category) clinical failure rate of cancer drugs. 28 Analyses of common mice ALS models demonstrate significant differences from human ALS. 29 The inability of animal ALS models to predict beneficial effects in humans with ALS is recognized. 30 More than twenty drugs have failed in clinical trials, and the only U.S. Food and Drug Administration (FDA)–approved drug to treat ALS is Riluzole, which shows notably marginal benefit on patient survival. 31 Animal models have also been unable to reproduce the complexities of human TBI. 32 In 2010, Maas et al. reported on 27 large Phase 3 clinical trials and 6 unpublished trials in TBI that all failed to show human benefit after showing benefit in animals. 33 Additionally, even after success in animals, around 172 and 150 drug development failures have been identified in the treatment of human AD 34 and inflammatory diseases, 35 respectively.

The high clinical failure rate in drug development across all disease categories is based, at least in part, on the inability to adequately model human diseases in animals and the poor predictability of animal models. 36 A notable systematic review, published in 2007, compared animal experimentation results with clinical trial findings across interventions aimed at the treatment of head injury, respiratory distress syndrome, osteoporosis, stroke, and hemorrhage. 37 The study found that the human and animal results were in accordance only half of the time. In other words, the animal experiments were no more likely than a flip of the coin to predict whether those interventions would benefit humans.

In 2004, the FDA estimated that 92 percent of drugs that pass preclinical tests, including “pivotal” animal tests, fail to proceed to the market. 38 More recent analysis suggests that, despite efforts to improve the predictability of animal testing, the failure rate has actually increased and is now closer to 96 percent. 39 The main causes of failure are lack of effectiveness and safety problems that were not predicted by animal tests. 40

Usually, when an animal model is found wanting, various reasons are proffered to explain what went wrong—poor methodology, publication bias, lack of preexisting disease and medications, wrong gender or age, and so on. These factors certainly require consideration, and recognition of each potential difference between the animal model and the human disease motivates renewed efforts to eliminate these differences. As a result, scientific progress is sometimes made by such efforts. However, the high failure rate in drug testing and development, despite attempts to improve animal testing, suggests that these efforts remain insufficient to overcome the obstacles to successful translation that are inherent to the use of animals. Too often ignored is the well-substantiated idea that these models are, for reasons summarized here, intrinsically lacking in relevance to, and thus highly unlikely to yield useful information about, human diseases. 41

Interspecies Differences in Physiology and Genetics

Ultimately, even if considerable congruence were shown between an animal model and its corresponding human disease, interspecies differences in physiology, behavior, pharmacokinetics, and genetics would significantly limit the reliability of animal studies, even after a substantial investment to improve such studies. In spinal cord injury, for example, drug testing results vary according to which species and even which strain within a species is used, because of numerous interspecies and interstrain differences in neurophysiology, anatomy, and behavior. 42 The micropathology of spinal cord injury, injury repair mechanisms, and recovery from injury varies greatly among different strains of rats and mice. A systematic review found that even among the most standardized and methodologically superior animal experiments, testing results assessing the effectiveness of methylprednisolone for spinal cord injury treatment varied considerably among species. 43 This suggests that factors inherent to the use of animals account for some of the major differences in results.

Even rats from the same strain but purchased from different suppliers produce different test results. 44 In one study, responses to 12 different behavioral measures of pain sensitivity, which are important markers of spinal cord injury, varied among 11 strains of mice, with no clear-cut patterns that allowed prediction of how each strain would respond. 45 These differences influenced how the animals responded to the injury and to experimental therapies. A drug might be shown to help one strain of mice recover but not another. Despite decades of using animal models, not a single neuroprotective agent that ameliorated spinal cord injury in animal tests has proven efficacious in clinical trials to date. 46

Further exemplifying the importance of physiological differences among species, a 2013 study reported that the mouse models used extensively to study human inflammatory diseases (in sepsis, burns, infection, and trauma) have been misleading. The study found that mice differ greatly from humans in their responses to inflammatory conditions. Mice differed from humans in what genes were turned on and off and in the timing and duration of gene expression. The mouse models even differed from one another in their responses. The investigators concluded that “our study supports higher priority to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory disease.” 47 The different genetic responses between mice and humans are likely responsible, at least in part, for the high drug failure rate. The authors stated that every one of almost 150 clinical trials that tested candidate agents’ ability to block inflammatory responses in critically ill patients failed.

Wide differences have also become apparent in the regulation of the same genes, a point that is readily seen when observing differences between human and mouse livers. 48 Consistent phenotypes (observable physical or biochemical characteristics) are rarely obtained by modification of the same gene, even among different strains of mice. 49 Gene regulation can substantially differ among species and may be as important as the presence or absence of a specific gene. Despite the high degree of genome conservation, there are critical differences in the order and function of genes among species. To use an analogy: as pianos have the same keys, humans and other animals share (largely) the same genes. Where we mostly differ is in the way the genes or keys are expressed. For example, if we play the keys in a certain order, we hear Chopin; in a different order, we hear Ray Charles; and in yet a different order, it’s Jerry Lee Lewis. In other words, the same keys or genes are expressed, but their different orders result in markedly different outcomes.

Recognizing the inherent genetic differences among species as a barrier to translation, researches have expressed considerable enthusiasm for genetically modified (GM) animals, including transgenic mice models, wherein human genes are inserted into the mouse genome. However, if a human gene is expressed in mice, it will likely function differently from the way it functions in humans, being affected by physiological mechanisms that are unique in mice. For example, a crucial protein that controls blood sugar in humans is missing in mice. 50 When the human gene that makes this protein was expressed in genetically altered mice, it had the opposite effect from that in humans: it caused loss of blood sugar control in mice. Use of GM mice has failed to successfully model human diseases and to translate into clinical benefit across many disease categories. 51 Perhaps the primary reason why GM animals are unlikely to be much more successful than other animal models in translational medicine is the fact that the “humanized” or altered genes are still in nonhuman animals.

In many instances, nonhuman primates (NHPs) are used instead of mice or other animals, with the expectation that NHPs will better mimic human results. However, there have been sufficient failures in translation to undermine this optimism. For example, NHP models have failed to reproduce key features of Parkinson’s disease, both in function and in pathology. 52 Several therapies that appeared promising in both NHPs and rat models of Parkinson’s disease showed disappointing results in humans. 53 The campaign to prescribe hormone replacement therapy (HRT) in millions of women to prevent cardiovascular disease was based in large part on experiments on NHPs. HRT is now known to increase the risk of these diseases in women. 54

HIV/AIDS vaccine research using NHPs represents one of the most notable failures in animal experimentation translation. Immense resources and decades of time have been devoted to creating NHP (including chimpanzee) models of HIV. Yet all of about 90 HIV vaccines that succeeded in animals failed in humans. 55 After HIV vaccine gp120 failed in clinical trials, despite positive outcomes in chimpanzees, a BMJ article commented that important differences between NHPs and humans with HIV misled researchers, taking them down unproductive experimental paths. 56 Gp120 failed to neutralize HIV grown and tested in cell culture. However, because the serum protected chimpanzees from HIV infection, two Phase 3 clinical trials were undertaken 57 —a clear example of how expectations that NHP data are more predictive than data from other (in this case, cell culture) testing methods are unproductive and harmful. Despite the repeated failures, NHPs (though not chimpanzees or other great apes) remain widely used for HIV research.

The implicit assumption that NHP (and indeed any animal) data are reliable has also led to significant and unjustifiable human suffering. For example, clinical trial volunteers for gp120 were placed at unnecessary risk of harm because of unfounded confidence in NHP experiments. Two landmark studies involving thousands of menopausal women being treated with HRT were terminated early because of increased stroke and breast cancer risk. 58 In 2003, Elan Pharmaceuticals was forced to prematurely terminate a Phase 2 clinical trial when an investigational AD vaccine was found to cause brain swelling in human subjects. No significant adverse effects were detected in GM mice or NHPs. 59

In another example of human suffering resulting from animal experimentation, six human volunteers were injected with an immunomodulatory drug, TGN 1412, in 2006. 60 Within minutes of receiving the experimental drug, all volunteers suffered a severe adverse reaction resulting from a life-threatening cytokine storm that led to catastrophic systemic organ failure. The compound was designed to dampen the immune system, but it had the opposite effect in humans. Prior to this first human trial, TGN 1412 was tested in mice, rabbits, rats, and NHPs with no ill effects. NHPs also underwent repeat-dose toxicity studies and were given 500 times the human dose for at least four consecutive weeks. 61 None of the NHPs manifested the ill effects that humans showed almost immediately after receiving minute amounts of the test drug. Cynomolgus and rhesus monkeys were specifically chosen because their CD28 receptors demonstrated similar affinity to TGN 1412 as human CD28 receptors. Based on such data as these, it was confidently concluded that results obtained from these NHPs would most reliably predict drug responses in humans—a conclusion that proved devastatingly wrong.

As exemplified by the study of HIV/AIDS, TGN 1412, and other experiences, 62 experiments with NHPs are not necessarily any more predictive of human responses than experiments with other animals. The repeated failures in translation from studies with NHPs belie arguments favoring use of any nonhuman species to study human physiology and diseases and to test potential treatments. If experimentation using chimpanzees and other NHPs, our closest genetic cousins, are unreliable, how can we expect research using other animals to be reliable? The bottom line is that animal experiments, no matter the species used or the type of disease research undertaken, are highly unreliable—and they have too little predictive value to justify the resultant risks of harms for humans, for reasons I now explain.

The Collective Harms That Result from Misleading Animal Experiments

As medical research has explored the complexities and subtle nuances of biological systems, problems have arisen because the differences among species along these subtler biological dimensions far outweigh the similarities , as a growing body of evidence attests. These profoundly important—and often undetected—differences are likely one of the main reasons human clinical trials fail. 63

“Appreciation of differences” and “caution” about extrapolating results from animals to humans are now almost universally recommended. But, in practice, how does one take into account differences in drug metabolism, genetics, expression of diseases, anatomy, influences of laboratory environments, and species- and strain-specific physiologic mechanisms—and, in view of these differences, discern what is applicable to humans and what is not? If we cannot determine which physiological mechanisms in which species and strains of species are applicable to humans (even setting aside the complicating factors of different caging systems and types of flooring), the usefulness of the experiments must be questioned.

It has been argued that some information obtained from animal experiments is better than no information. 64 This thesis neglects how misleading information can be worse than no information from animal tests. The use of nonpredictive animal experiments can cause human suffering in at least two ways: (1) by producing misleading safety and efficacy data and (2) by causing potential abandonment of useful medical treatments and misdirecting resources away from more effective testing methods.

Humans are harmed because of misleading animal testing results. Imprecise results from animal experiments may result in clinical trials of biologically faulty or even harmful substances, thereby exposing patients to unnecessary risk and wasting scarce research resources. 65 Animal toxicity studies are poor predictors of toxic effects of drugs in humans. 66 As seen in some of the preceding examples (in particular, stroke, HRT, and TGN1412), humans have been significantly harmed because investigators were misled by the safety and efficacy profile of a new drug based on animal experiments. 67 Clinical trial volunteers are thus provided with raised hopes and a false sense of security because of a misguided confidence in efficacy and safety testing using animals.

An equal if indirect source of human suffering is the opportunity cost of abandoning promising drugs because of misleading animal tests. 68 As candidate drugs generally proceed down the development pipeline and to human testing based largely on successful results in animals 69 (i.e., positive efficacy and negative adverse effects), drugs are sometimes not further developed due to unsuccessful results in animals (i.e., negative efficacy and/or positive adverse effects). Because much pharmaceutical company preclinical data are proprietary and thus publicly unavailable, it is difficult to know the number of missed opportunities due to misleading animal experiments. However, of every 5,000–10,000 potential drugs investigated, only about 5 proceed to Phase 1 clinical trials. 70 Potential therapeutics may be abandoned because of results in animal tests that do not apply to humans. 71 Treatments that fail to work or show some adverse effect in animals because of species-specific influences may be abandoned in preclinical testing even if they may have proved effective and safe in humans if allowed to continue through the drug development pipeline.

An editorial in Nature Reviews Drug Discovery describes cases involving two drugs in which animal test results from species-specific influences could have derailed their development. In particular, it describes how tamoxifen, one of the most effective drugs for certain types of breast cancer, “would most certainly have been withdrawn from the pipeline” if its propensity to cause liver tumor in rats had been discovered in preclinical testing rather than after the drug had been on the market for years. 72 Gleevec provides another example of effective drugs that could have been abandoned based on misleading animal tests: this drug, which is used to treat chronic myelogenous leukemia (CML), showed serious adverse effects in at least five species tested, including severe liver damage in dogs. However, liver toxicity was not detected in human cell assays, and clinical trials proceeded, which confirmed the absence of significant liver toxicity in humans. 73 Fortunately for CML patients, Gleevec is a success story of predictive human-based testing. Many useful drugs that have safely been used by humans for decades, such as aspirin and penicillin, may not have been available today if the current animal testing regulatory requirements were in practice during their development. 74

A further example of near-missed opportunities is provided by experiments on animals that delayed the acceptance of cyclosporine, a drug widely and successfully used to treat autoimmune disorders and prevent organ transplant rejection. 75 Its immunosuppressive effects differed so markedly among species that researchers judged that the animal results limited any direct inferences that could be made to humans. Providing further examples, PharmaInformatic released a report describing how several blockbuster drugs, including aripiprazole (Abilify) and esomeprazole (Nexium), showed low oral bioavailability in animals. They would likely not be available on the market today if animal tests were solely relied on. Understanding the implications of its findings for drug development in general, PharmaInformatic asked, “Which other blockbuster drugs would be on the market today, if animal trials would have not been used to preselect compounds and drug-candidates for further development?” 76 These near-missed opportunities and the overall 96 percent failure rate in clinical drug testing strongly suggest the unsoundness of animal testing as a precondition of human clinical trials and provide powerful evidence for the need for a new, human-based paradigm in medical research and drug development.

In addition to potentially causing abandonment of useful treatments, use of an invalid animal disease model can lead researchers and the industry in the wrong research direction, wasting time and significant investment. 77 Repeatedly, researchers have been lured down the wrong line of investigation because of information gleaned from animal experiments that later proved to be inaccurate, irrelevant, or discordant with human biology. Some claim that we do not know which benefits animal experiments, particularly in basic research, may provide down the road. Yet human lives remain in the balance, waiting for effective therapies. Funding must be strategically invested in the research areas that offer the most promise.

The opportunity costs of continuing to fund unreliable animal tests may impede development of more accurate testing methods. Human organs grown in the lab, human organs on a chip, cognitive computing technologies, 3D printing of human living tissues, and the Human Toxome Project are examples of new human-based technologies that are garnering widespread enthusiasm. The benefit of using these testing methods in the preclinical setting over animal experiments is that they are based on human biology. Thus their use eliminates much of the guesswork required when attempting to extrapolate physiological data from other species to humans. Additionally, these tests offer whole-systems biology, in contrast to traditional in vitro techniques. Although they are gaining momentum, these human-based tests are still in their relative infancy, and funding must be prioritized for their further development. The recent advancements made in the development of more predictive, human-based systems and biological approaches in chemical toxicological testing are an example of how newer and improved tests have been developed because of a shift in prioritization. 78 Apart from toxicology, though, financial investment in the development of human-based technologies generally falls far short of investment in animal experimentation. 79

The unreliability of applying animal experimental results to human biology and diseases is increasingly recognized. Animals are in many respects biologically and psychologically similar to humans, perhaps most notably in the shared characteristics of pain, fear, and suffering. 80 In contrast, evidence demonstrates that critically important physiological and genetic differences between humans and other animals can invalidate the use of animals to study human diseases, treatments, pharmaceuticals, and the like. In significant measure, animal models specifically, and animal experimentation generally, are inadequate bases for predicting clinical outcomes in human beings in the great bulk of biomedical science. As a result, humans can be subject to significant and avoidable harm.

The data showing the unreliability of animal experimentation and the resultant harms to humans (and nonhumans) undermine long-standing claims that animal experimentation is necessary to enhance human health and therefore ethically justified. Rather, they demonstrate that animal experimentation poses significant costs and harms to human beings. It is possible—as I have argued elsewhere—that animal research is more costly and harmful, on the whole, than it is beneficial to human health. 81 When considering the ethical justifiability of animal experiments, we should ask if it is ethically acceptable to deprive humans of resources, opportunity, hope, and even their lives by seeking answers in what may be the wrong place. In my view, it would be better to direct resources away from animal experimentation and into developing more accurate, human-based technologies.

Aysha Akhtar , M.D., M.P.H., is a neurologist and preventive medicine specialist and Fellow at the Oxford Centre for Animal Ethics, Oxford, United Kingdom.

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105 Animal Testing Essay Topic Ideas & Examples

Looking for interesting animal testing topics to research and write about? This field is truly controversial and worth studying!

• 🌶️ Titles: Catchy & Creative
• 🐶 Essay: How to Write
• 🏆 Best Essay Examples
• 📌 Good Topics to Research
• 🎯 Most Interesting Topics to Write about

❓ Animal Testing Research Questions

In your animal testing essay, you might want to explore the historical or legal perspective, focus on the issue of animal rights, or discuss the advantages or disadvantages of animal testing in medicine, pharmacology, or cosmetic industry. We’ve gathered the most creative and catchy animal testing titles and added top animal testing essay examples. There are also useful tips on making and outline, formulating a thesis, and creating a hook sentence for your animal testing essay.

🌶️ Animal Testing Titles: Catchy & Creative

• What would life be like without animal testing?
• Animal testing: the cruelest experiments.
• AWA: why does not it protect all animals?
• What if animals experimented on humans?
• In the skin of a guinea pig: a narrative essay.
• Opposing animal testing: success stories.
• Animal-tested products: should they be destroyed?
• What have we gained from experiments on animals?
• Animal testing and cancer research: past and present.

🐶 Animal Testing Essay: How to Write

Animal testing has been an acute problem for a long time. Scientists and pharmaceutical firms use this approach to test cosmetics, foods, and other products people use daily.

Essays on animal testing are important because they highlight the significance of the problem. Writing outstanding animal testing essays requires extensive research and dedication.

We have prepared some do’s and don’ts for your excellent essay. But first, you should select a topic for your paper. Here are the examples of animal testing essay topics you can choose from:

• The question of animal intelligence from the perspective of animal testing
• Animal testing should (not) be banned
• How animal testing affects endangered species
• The history and consequences of animal testing
• The controversy associated with animal testing
• Animal Bill of Rights: Pros and cons
• Is animal testing necessary?

Remember that these animal testing essay titles are just the ideas for your paper. You are free to select other relevant titles and topics for discussion, too. Once you have selected the problem for your essay, you can start working on the paper. Here are some do’s of writing about animal testing:

• Do extensive preliminary research on the issue you have selected. You should be aware of all the problems associated with your questions, its causes, and consequences. Ask your professor about the sources you can use. Avoid relying on Wikipedia and personal blogs as your primary sources of information.
• Develop a well-organized outline and think of how you will structure your paper. Think of the main animal testing essay points and decide how you can present them in the paper. Remember to include introductory and concluding sections along with several body paragraphs.
• Start your paper with a hooking sentence. An animal testing essay hook should grab the reader’s attention. You can present an interesting question or statistics in this sentence.
• Include a well-defined thesis statement at the end of the introductory section.
• Your reader should understand the issue you are discussing. Explain what animal testing is, provide arguments for your position, and support them with evidence from your research.
• Discuss alternative perspectives on the issue if you are working on a persuasive essay. At the same time, you need to show that your opinion is more reliable than the opposing ones.
• Remember that your paper should not be offensive. Even if you criticize animal testing, stick to the formal language and provide evidence of why this practice is harmful.

There are some important points you should avoid while working on your paper. Here are some important don’ts to remember:

• Avoid making claims if you cannot reference them. Support your arguments with evidence from the literature or credible online sources even if you are writing an opinion piece. References will help the reader to understand that your viewpoint is reliable.
• Do not go over or below the word limit. Stick to your professor’s instructions.
• Avoid copying the essays you will find online. Your paper should be plagiarism-free.
• Avoid making crucial grammatical mistakes. Pay attention to the word choice and sentence structures. Check the paper several times before sending it for approval. If you are not sure whether your grammar is correct, ask a friend to look through the paper for you.

Do not forget to look at some of our free samples that will help you with your paper!

Animal Testing Hook Sentence

Your animal testing essay should start with a hook – an opening statement aiming to grab your reader’s attention. A good idea might be to use an impressive fact or statistics connected to experiments on animals:

• More than 100 million animals are killed in US laboratories each year.
• Animal Welfare Act (AWA) does not cover 99% animals used in experiments: according to it, rats, birds, reptiles, and fish are not animals.
• More than 50% adults in the US are against animal testing.

🏆 Best Animal Testing Essay Examples

• Animal Testing: Should Animal Testing Be Allowed? — Argumentative Essay It is crucial to agree that animal testing might be unethical phenomenon as argued by some groups; nonetheless, it should continue following its merits and contributions to the humankind in the realms of drug investigations […]
• Should Animals Be Used in Medical Research? It is therefore possible to use animals while testing the dangers and the toxicity of new drugs and by so doing; it is possible to protect human beings from the dangers that can emanate from […]
• Cosmetic Testing on Animals The surface of the skin or near the eyes of such animals is meant to simulate that of the average human and, as such, is one of easiest methods of determining whether are particular type […]
• Experimentation on Animals However, critics of experimenting with animals argue that animals are subjected to a lot of pain and suffering in the course of coming up with scientific breakthroughs which in the long run may prove futile.
• Animal Testing: History and Arguments Nevertheless, that law was more focused on the welfare of animals in laboratories rather than on the prohibition of animal testing.
• Animal Experiments and Inhuman Treatment Although the results of such a laboratory may bring answers to many questions in medicine, genetics, and other vital spheres, it is frequently a case that the treatment of such animals is inhumane and cruel. […]
• Animal Testing and Ethics I believe it is also difficult to develop efficient legislation on the matter as people have different views on animal research and the line between ethical and unethical is blurred in this area.
• The Debate on Animal Testing The purpose of this paper is to define animal testing within a historical context, establish ethical and legal issues surrounding the acts, discuss animal liberation movements, arguments in support and against the act of animal […]
• Animal Testing in Medicine and Industry Animal testing is the inescapable reality of medicine and industry. However, between human suffering and animal suffering, the former is more important.
• Preclinical Testing on Animals The authors argue that despite the recent decline in the level of quality and transparency of preclinical trials, the scientific communities should always rely on animal testing before moving to human subjects and the subsequent […]
• Using Animals in Medical Research and Experiments While discussing the use of animals in medical research according to the consequentialist perspective, it is important to state that humans’ preferences cannot be counted higher to cause animals’ suffering; humans and animals’ preferences need […]
• Laboratory Experiments on Animals: Argument Against In some cases, the animals are not given any painkillers because their application may alter the effect of the medication which is investigated.
• Animal Testing From Medical and Ethical Viewpoints Striving to discover and explain the peculiarities of body functioning, already ancient Greeks and Romans resorted to vivisecting pigs; the scientific revolution of the Enlightenment era witnessed animal testing becoming the leading trend and a […]
• Negative Impacts of Animal Testing To alter these inhumane laws, we should organize a social movement aiming at the reconsideration of the role of animals in research and improvement of their positions.
• Animal Testing: Long and Unpretty History Nevertheless, that law was more focused on the welfare of animals in laboratories rather than on the prohibition of animal testing.
• Animal Testing as an Unnecessary and Atrocious Practice Such acts of violence could be partially excused by the necessity to test medications that are developed to save human lives however, this kind of testing is even more inhumane as it is ineffective in […]
• Animal Testing and Environmental Protection While the proponents of animal use in research argued that the sacrifice of animals’ lives is crucial for advancing the sphere of medicine, the argument this essay will defend relates to the availability of modern […]
• Animal Testing for Scientific Research Despite the fact that the present-day science makes no secret of the use of animals for research purposes, not many people know what deprivation, pain, and misery those animals have to experience in laboratories.
• Animal Testing: History and Ethics Moreover, in the twelfth century, another Arabic physician, Avenzoar dissected animals and established animal testing experiment in testing surgical processes prior to their application to man. Trevan in 1927 to evaluate the effectiveness of digitalis […]
• Animal Testing Effects on Psychological Investigation In this context, ethical considerations remain a central theme in psychological research.”Ethics in research refers to the application of moral rules and professional codes of conduct to the collection, analysis, reporting, and publication of information […]
• Genetic Modification and Testing: Ethical Considerations It is done on a molecular level by synthesizing DNA, generating sequences and then inserting the received product into the organism which will be the carrier of the outcome. Another possibility is that the time […]
• Animal Testing: Why It Is Still Being Used The major reason for such “devotion” to animal testing can be explained by the fact that alternative sources of testing are insufficient and too inaccurate to replace conventional way of testing.
• Effects of Animal Testing and Alternatives Another challenge to the proponents of animal testing is related to dosage and the time line for a study. Animal rights values rebuff the notion that animals should have an importance to human beings in […]
• Ethics Problems in Animal Experimentation In spite of the fact that it is possible to find the arguments to support the idea of using animals in experiments, animal experimentation cannot be discussed as the ethical procedure because animals have the […]
• Animal Testing: Ethical Dilemmas in Business This means that both humans and animals have rights that need to be respected, and that is what brings about the many dilemmas that are experienced in this field.
• Should animals be used for scientific research? Therefore, considering the benefits that have been accrued from research activities due to use of animals in scientific research, I support that animals should be used in scientific research.
• Use of Animals in Research Testing: Ethical Justifications Involved The present paper argues that it is ethically justified to use animals in research settings if the goals of the research process are noble and oriented towards the advancement of human life.
• Ethical Problems in Animal Experimentation The banning of companies from testing on animals will force the manufacturers to use conventional methods to test their drugs and products.
• Utilitarianism for Animals: Testing and Experimentation There are alternatives in testing drugs such as tissue culture of human cells and hence this is bound to be more accurate in the findings.
• Use of Animals in Biological Testing Thus, these veterinarians have realized that the results that are realized from the animal research are very crucial in the improvement of the health of human being as well as that of animals.
• Medical Research on Animals Should be Forbidden by Law Vaccines and treatment regimes for various diseases that previously led to the death of humans were all discovered through research on animals.
• Psychoactive Drug Testing on Animals The alterations in behavioral traits of animals due to psychoactive drugs are primarily attributed to the changes in the brain functions or inhibition of certain brain components in animals which ultimately translates to changes in […]
• Negative Impacts of Animal Testing In many instances it can be proofed that drugs have been banned from the market after extensive research on animal testing and consuming a lot of cash, because of the dire effects that they cause […]

📌 Good Animal Testing Topics to Research

• Monkeys Don’t Like Wearing Makeup: Animal Testing In The Cosmetics Industry
• Animal Testing – Should Animal Experimentation Be Permitted
• Essay Animal Testing and In Vitro Testing as a Replacement
• Animal Testing : A Better Knowledge Of Human Body
• The Importance Of Animal Testing For Evaluating Consumer Safety
• The Issues on Animal Testing and the Alternative Procedures to Avoid the Use of the Inhuman Experimentation
• An Alternative to the Harsh and Unnecessary Practices of Animal Testing for Products, Drugs, Chemicals and Other Research
• The Unethical Use of Animals and the Need to Ban Animal Testing for Medical Research Purposes in the United States
• An Argument in Favor of Animal Testing for the Purpose of Clinical Research
• An Argument Against Animal Testing and the Banning of the Practice in the United States
• The Debate About the Ethics of Animal Testing and Its Effects on Us
• An Argument in Favor of Animal Testing as Beneficial to Human Health Research
• Animal Testing and the Reasons Why It Should Be Illegal
• The Principles of the Animal Testing From the Human Perspective
• The Ethical Issues on the Practice of Animal Testing to Test Cosmetics and Drugs
• Stopping Animal Testing and Vivisection by Passing a Bill against Animal Cruelty

🎯 Most Interesting Animal Testing Topics to Write about

• An Argument Against Animal Testing of Consumer Products and Drugs
• The Consequences and Unethical Practice of Animal Testing for Medical Training and Experiments
• How Do The Contributions Of Animal Testing To Global Medical
• Ways To Improve Animal Welfare After Premising The Animal Testing
• Animal Testing – Necessary or Barbaric and Wrong?
• Animal Testing And Its Impact On The Environment
• Animal Testing and Its Contribution to the Advancement of Medicine
• Cosmetics and Animal Testing: The Cause of Death and Mistreatment
• Animal Testing And People For The Ethical Treatment Of Animals
• Animal Rights Activists and the Controversial Issue of Animal Testing
• A History and the Types of Animal Testing in the Medical Area
• Argumentation on Medical Benefits of Animal Testing
• An Analysis of the Concept of Animal Testing Which Lowers the Standard of Human Life
• Is The Humane Society International Gave For Animal Testing
• A Discussion of Whether Animal Testing Is Good for Mankind or Violation of Rights
• The Ethics Of Animal Testing For Vaccine Development And Potential Alternatives
• The Good and Bad of Human Testing and Animal Testing
• What Should the Government Do About Animal Testing?
• Why Does Animal Testing Lower Our Standard of Living?
• Should Animals Be Used in Research?
• Why Should Animal Testing Be Accepted in the World?
• How Does Technology Impact Animal Testing?
• Why Should Animal Testing Be Illegal?
• Should Animal Testing Remain Legal?
• Why Should Animal Testing Be Banned?
• Can the Animal Testing Done to Find Cures for Diseases Be Humane?
• Does Animal Testing Really Work?
• Why Can’t Alternatives Like Computers Replace Research Animals?
• Should Animal Testing Continue to Test Cures for Human Diseases?
• How Does Animal Testing Effect Medicine?
• Should Animal Testing Continue or Be Stopped?
• What Are Advantages and Disadvantages of Animal Testing?
• Why Can Animal Testing Save Our Lives?
• Is Stem Cell Research Beginning of the End of Animal Testing?
• Do Beauty Products Suffer From Negative Publicity if They Conduct Trials on Animals?
• Should Medicine Trials Be Conducted?
• Can Results of Animal Testing Be Generalized to Adults?
• What Are the Origin and History of Animal Testing?
• Why Are Animals Needed to Screen Consumer Products for Safety When Products Tested by Alternative Methods, Are Available?
• How Much Does an Animal Suffer Due to Testing?
• What Is the Effectiveness of Animal Rights Groups in Stopping Animal Testing?
• How Do We Learn From Biomedical Research Using Animals?
• Who Cares for Animals in Research?
• How Do Laboratory Animal Science Professionals Feel About Their Work?
• Why Are There Increasing Numbers of Mice, Rats, and Fish Used in Research?
• How Can We Be Sure Lost or Stolen Pets Are Not Used in Research?
• Why Do Clinical Trials in Humans Require Prior Animal Testing?
• Vegetarianism Essay Ideas
• Animal Welfare Ideas
• Bioethics Titles
• Wildlife Ideas
• Extinction Research Topics
• Hunting Questions
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All Your Questions About Experiments on Animals Answered

What is animal testing? Every year in the U.S., tens of millions animals suffer and die in chemical, drug, food, and product tests. Animals are used in medical training exercises and in huge numbers in government- and taxpayer-funded curiosity-driven experiments at universities. They also suffer and die for classroom biology experiments and dissection, even though modern, non-animal methods have repeatedly been shown to have more educational value and save schools money.

Studies published in prestigious medical journals have repeatedly shown that animal experimentation wastes precious resources and lives.  The most recent independent study shows that 90% of basic research , most of which involves animals, fails to lead to treatments for humans.

Check out these facts about animal testing to learn more:

What is animal testing.

Animal testing refers to the practice of performing unnatural and often painful experiments on animals held captive in stressful laboratory settings, often in the misguided belief that the results of the tests will be applicable to humans. At the conclusion of most experiments, the subjects—millions of them per year—are killed.

Which Animals Are Used in Tests?

Right now, millions of mice , rats , rabbits , monkeys , cats , dogs , fish , and other animals used in tests are locked inside cages in laboratories across the country. They languish in pain, suffer from extreme frustration, ache with loneliness, and long to be free.

Exact numbers aren’t available, because mice, rats, birds, and cold-blooded animals—who make up more than 99% of animals used in experiments—are not protected under the federal Animal Welfare Act and their numbers don’t even have to be reported. These sentient beings aren’t even defined as “animals” under this act, which is the only federal law offering any sort of protection for animals.

Is Animal Testing Cruel?

Experimenting on animals is not only cruel but also completely unnecessary and unethical. The unnatural and stressful conditions of captivity make it even more unlikely that the results of animal tests can be applied to humans.

Published studies show that 90% of our fellow primates who are used in laboratories exhibit abnormal behavior patterns caused by the psychological stress, social isolation, and confinement to barren enclosures that they’re forced to endure. Many go insane, rocking back and forth, pacing endlessly inside cages, and doing repetitive motions such as back-flipping. They even engage in acts of self-mutilation, including tearing out their own hair and biting their own flesh.

Experiments on Animals at Colleges and Universities

The federal government and many health charities waste billions of dollars—including money from U.S. taxpayers—on animal experiments at universities and private laboratories, instead of supporting promising non-animal studies that could actually benefit humans.

Right now, animals in university laboratories are being mutilated, poisoned, deprived of food and water, immobilized in restraint devices, infected with painful and deadly diseases, burned, electrocuted, irradiated, addicted to drugs, and psychologically tortured. None of the thousands of experiments conducted on animals every year at universities are required by law.

You can join PETA in opposing these cruel and useless tests by taking action today:

Are Tests on Animals Legal?

Yes. U.S. law allows for animals to be burned, shocked, poisoned, isolated, starved, drowned, addicted to drugs, and brain-damaged. No experiment, no matter how painful or trivial, is prohibited—and painkillers are often not required. Even when alternatives to the use of animals are available, the law doesn’t require that they be used—and often, they aren’t.

How Does PETA Help Animals Used in Experiments?

PETA’s vivid demonstrations and undercover investigations alert the public to wasteful, cruel, and useless experiments on animals, often ones occurring right under their noses. We actively campaign to get animals out of laboratories—and win. Check out a list of our latest victories .

The PETA International Science Consortium Ltd. works with agencies around the world to reduce the number of animals used in tests. PETA’s scientists are at the forefront of humane and modern methods, promoting groundbreaking non-animal tests and eliminating requirements for experiments on animals by sharing existing research and data with companies and governments.

PETA scientists sat in as the U.S. Environmental Protection Agency made the historic announcement that it would end toxicity tests on mammals—something we’ve pushed the agency to do for nearly 20 years.

Which Cosmetics and Personal-Care Companies Don’t Conduct Tests on Animals?

Neither the U.S. Food and Drug Administration nor the U.S. Consumer Product Safety Commission requires that cosmetics be tested on animals. There are already sufficient safety data and many non-animal methods available to make animal testing obsolete for these products.

Thankfully, most cosmetics companies have already banned tests on animals as a result of PETA’s campaigns and consumer pressure. However, some sell products in countries where tests on animals are required. PETA’s searchable Global Beauty Without Bunnies list makes it easy to find cruelty-free companies that have committed to never testing their cosmetics or household cleaning products on animals—here or abroad.

PETA also works with large food and beverage companies to end the practice of testing ingredients on animals in order to make health claims about products. Dozens of companies have banned all tests on animals for this purpose. You can rest assured knowing that the delicious vegan foods you’ll find recommended in our Living section come from such companies.

What Percentage of Animal Tests Fail?

Studies published in prestigious medical journals have repeatedly shown that animal experimentation wastes precious resources and lives. More than 90% of basic research , most of which involves animals, fails to lead to treatments for humans. And more than 95% of new drugs that test safe and effective in animals go on to fail in human clinical trials. Yet around the world, millions of animals continue to be used in experiments and then killed.

History of Animal Testing and Animal-Free Medical Advances

Between 1900 and 2000, life expectancy in the U.S. increased from 47 to 77 years. Although animal experimenters are often credited with this progress, medical historians report that improved nutrition and sanitation as well as other behavioral and environmental factors—rather than anything learned from tormenting animals—are responsible for this increased longevity.

Epidemiological studies have led to some of the most important breakthroughs, including the discovery of the relationship between cholesterol and heart disease and between smoking and cancer, the development of X-rays, and the isolation of the AIDS virus.

While experiments on animals have been conducted during the course of some important discoveries, this doesn’t mean that they were vital to the discovery of human-health treatments or that the same discoveries wouldn’t have been made anyway without using animals.

Take a trip through time using PETA’s interactive timeline, “ Without Consent ,” to learn about almost 200 stories of twisted animal experiments from the past century.

Animal Testing Alternatives: Can Science Progress Without Tests on Animals?

Today—because experiments on animals are cruel and expensive and their results are generally inapplicable to humans—the world’s most forward-thinking scientists are developing and using methods for studying diseases and testing products that replace animals and are actually relevant to human health.

Alternatives to animal testing include sophisticated tests using human cells and tissues (also known as in vitro methods), organs-on-chips, advanced computer-modeling techniques (often referred to as in silico models), and studies with human volunteers. These and other non-animal methods are humane, and they aren’t hindered by species differences that make applying animal test results to humans difficult or impossible. Also, they usually take less time and money to complete.

Why Should Animal Testing Be Banned?

In addition to the many reasons listed above, testing on animals is wasteful, violent, unproductive, and speciesist . Animals are not ours to use for experiments. They have their own wants, interests, needs, and feelings—independent of what purpose they might serve humans. In short, they are their own people and they don’t consent to being tortured and killed in laboratories.

Human wellness is more likely to be advanced by devoting resources to the development of non-animal test methods, which have the potential to be cheaper, faster, and more relevant to our bodies and health.

Support PETA’s Efforts to Help Animals in Laboratories

PETA makes it easy to take action to help animals suffering in experiments. Check out the page below, which makes it quick and easy to urge experimenters to end tests on animals:

From PETA and executive producer Bill Maher, the new docuseries ‘The Failed Experiment’ exposes what most people don’t know about experiments on animals.

Related Posts

For years, PETA scientists have urged regulators to accept non-animal methods for pyrogen testing instead of using horseshoe crab blood.

How did PETA’s Silver Spring monkey case rock the boat and make humans question the ways in which we treat our fellow animals? Listen to this interview with Ingrid Newkirk.

We did it! After hearing from PETA and thousands of our supporters, AELF FlightService has agreed to stop flying monkeys to their deaths in U.S. laboratories.

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“Almost all of us grew up eating meat, wearing leather, and going to circuses and zoos. We never considered the impact of these actions on the animals involved. For whatever reason, you are now asking the question: Why should animals have rights? ”

— Ingrid E. Newkirk, PETA President and co-author of Animalkind

Text CRAZY to 73822 to take action for chimpanzees suffering in human homes & roadside zoos! Then watch Chimp Crazy, HBO’s new docuseries to learn more.

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30 Thought-Provoking Debate Topics About Animal Testing

Animal testing is a highly debated topic among scientists, animal rights activists, and the general public. While some argue that animal testing is necessary for the development of life-saving drugs and medical treatments, others believe that it is cruel and unethical to use animals for experimentation. The debate over animal testing is complex and multifaceted, with arguments on both sides that are worth considering.

If you’re going to have a classroom debate about this topic, then these 30 debate topics about animal testing are ideal. These topics cover a range of perspectives and issues related to animal testing and can serve as a starting point for further research and discussion.

Animal Testing: Debate Topics

Download and print.

Download and print a PDF of these animal testing debate topics.

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5 burning questions about Missouri’s mysterious H5 bird flu case

Could raw milk — or a cat — help explain how a person who had no contact with animals caught the virus.

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By Helen Branswell

Sept. 8, 2024

Senior Writer, Infectious Diseases

News that a person in Missouri contracted H5 bird flu despite having no known contact with infected animals or birds — in other words, no evident route of infection — raises pressing questions public health officials are surely scurrying to answer.

The rationale for that urgency is this: An unexplained H5 infection raises the possibility of person-to-person spread of a flu virus that has never before circulated in humans, and to which people would not have immunity. And this with a dangerous flu virus that scientists have long feared could someday trigger a pandemic.

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After all, the 2009 H1N1 pandemic was first noticed when two children in California who had no contact with pigs or with each other were diagnosed with flu infections caused by a virus that had previously been circulating in swine. 

To be clear, it is far too soon to conclude this infection can’t be linked to some direct or indirect exposure to infected animals or birds, or to some farm product contaminated with the virus. 

But there are, as we noted, questions that need to be answered, and the sooner the better. Here are five.

What is being done to investigate the situation?

Word of the infection emerged late Friday when the Missouri Department of Health and Senior Services issued a press release , followed shortly by a statement from The Centers for Disease Control and Prevention; neither provided much information. The CDC statement said Missouri was conducting the on-the-ground investigation to look for the source of the individual’s infection.

Flu experts watching from afar are puzzled by the seeming lack of urgency. They wonder why the CDC hasn’t sent a team to the state, and why health officials waited so long to make the case public.

Their concerns add to criticism that the entire U.S. response to the outbreak of H5N1 viruses in dairy cattle has been lethargic; a number of critics have suggested if this outbreak were happening elsewhere, the U.S. would be up in arms about the tenor of the response. The concern is that if the virus, which is genetically wired to infect birds, adapts to be able to spread efficiently among mammals, that brings it a big step closer to being able to transmit among people.

“I would want to see a ‘better safe than sorry’ investigation,” said Marion Koopmans, head of the department of viroscience at the Erasmus Medical Center in Rotterdam, the Netherlands, said about the response to the Missouri case.

For Koopmans, what is being done to crack the mystery of how this person was infected tops the list of questions that need to be answered. “I would want to see a wide net cast here,” she said, such as looking to see if there is any evidence of hidden chains of person-to-person transmission of the virus. It “does not have to be all in the public eye, but I would want to know this is [being] taken up very seriously.” 

The fact that the case was only announced publicly two weeks after the individual was hospitalized and after the person had recovered and was discharged, seems like a missed opportunity to Angela Rasmussen, a virologist who specializes in emerging infectious diseases at at the University of Saskatchewan’s Vaccine and Infectious Disease Organization in Saskatoon, Canada. Local doctors should have been alerted quickly so they could be on the lookout for other such cases, she said.

“If there is human-to-human transmission, it is critical to carry out the [epidemiologic] investigation as rapidly and efficiently as possible, so the choice to drag their feet and give no details about follow up is mystifying and reflects very poorly on both Missouri state and federal epidemic response capacity and practice,” Rasmussen told STAT in an email.

Thomas Peacock would like to know if people investigating the case have or are planning to draw blood samples from close contacts of the infected person to look for evidence of H5 infections that might have gone undetected. Peacock is an influenza virologist at Britain’s Pirbright Institute, which focuses on controlling viral illnesses in animals.

He believes another explanation will eventually be arrived at, but if it turns out this case involved human-to-human transmission, “the U.S. can’t just sit on its thumbs anymore.”

Is this the same H5 virus that is spreading in cows?

The outbreak in dairy cattle has infected nearly 200 herds in 14 states — that we know of. Missouri hasn’t reported any infections in cows. However, farmers in many places have refused to test their cows. So there could be a lot more of the virus in the country than is currently known.

The virus causing the outbreak in cows is highly pathogenic avian influenza — sometimes shortened to HPAI — of the H5N1 subtype. That’s a family of viruses. The specific version in cows is called clade 2.3.4.4b, genotype B3.13. 

As of Friday, all that was known about the Missouri case was that the individual was infected with an H5 virus. The CDC was still working to try to figure out the neuraminidase of the virus, the N of its name. Sometimes that isn’t possible, for instance if there isn’t a lot of virus in the sample from the patient. 

The CDC is also working to record the genetic sequence of the virus. A sequence could help solve the source of the virus, by allowing a comparison of the virus from the person to other known versions of the virus. 

“Honestly, my assumption is it’s going to be high path H5N1. And probably if it is, it’s the bovine one, because there’s just a ton of that out at the moment,” said Peacock.

Rasmussen noted that knowing the N number of the virus is important because influenza A viruses — H5N1 is a flu A virus — can swap genes with each other, creating what are known as reassortants. That process could create a new virus that is better able to infect people, she said. 

How sick was this individual? Was he or she hospitalized for influenza symptoms, or for other reasons?

The Missouri press release gives very sparse details about the infected individual, and says that for patient privacy, no additional information will be forthcoming. 

The individual who tested positive went into the hospital on Aug. 22. The person had “underlying medical conditions” — though there are no details about how many, and how serious they are. There is no indication of the person’s age, though if it were a child, the press release likely would have said so. It states that the person recovered and was discharged from the hospital. It doesn’t indicate for how long the person was hospitalized or whether any of that time was spent in intensive care.

Why does it matter how ill the person was, and whether it was the flu that prompted the hospitalization or something else? There have been 13 other H5 cases in the U.S. this year, all directly or indirectly related to the outbreak in cows. All of these people had very mild illnesses.

If this individual’s H5 infection was severe enough to require hospitalization, that broadens the picture of the spectrum of illness that 2.3.4.4b B3.13 viruses can trigger. And it would suggest we shouldn’t assume we know how this virus would behave, if it starts to spread among people.

“It is important to know what this [illness] looks like in people, as well as to understand underlying medical conditions that might change a patient’s risk profile,” Rasmussen said.

Did this person truly have no contact with infected animals or birds? Does this individual have a cat that is allowed outdoors?

The press releases issued by the state and the CDC stressed that this is the first H5 case in the country in a person without an occupational exposure to infected cows or poultry. “The patient has reported no exposure to animals,” Missouri said. 

But is it possible the person had indirect exposure, for instance, contact with farmworkers who might have been exposed to infected poultry or cows? Some suspected H5N1 transmission events between people in other countries have occurred among people whose close household contacts interacted with infected animals, Peacock noted.

Other experts have questioned whether the individual had bird feeders, which could potentially have exposed him or her to wild bird droppings. They have also wondered whether the household had any cats. There have been a number of reports of infected cats on farms with H5N1-infected dairy cows, assumed to be caused by consumption of infected milk. Cats also could become infected through encounters with infected wild birds.

Did this person consume raw milk?

One of the big questions in social media discussions among scientists this weekend is whether this individual drank raw milk , or consumed raw milk products. Unpasteurized milk from infected cows contains extraordinarily high amounts of the virus. Laboratory experiments have shown feeding contaminated raw milk to mice can induce severe disease . Many of the farms with infected cats have reported deaths among the animals.

It’s not known what risks drinking H5N1-laced milk pose for people but scientists have been worried it could induce disease . Peacock, for one, is surprised that infections linked to raw milk consumption haven’t been identified yet.

“The obvious question I would ask is: Have you ruled out that they’re not someone who’s got a big tub of raw milk in their fridge? Because that just seems like such an obvious route for a cryptic infection,” he said.

Rasmussen agreed that exploring this possibility is critical, saying “if this is [due to] raw milk consumption, this would be very valuable information to have about the feasibility and risk of this exposure route.”

About the reporting

STAT’s investigation is based on interviews with nearly 100 people around the country, including incarcerated patients and grieving families, prison officials, and legal and medical experts. Reporter Nicholas Florko also filed more than 225 public records requests and combed through thousands of pages of legal filings to tell these stories. His analysis of deaths in custody is based on a special data use agreement between STAT and the Department of Justice.

You can read more about the reporting for this project and the methodology behind our calculations.

The series is the culmination of a reporting fellowship sponsored by the Association of Health Care Journalists and supported by The Commonwealth Fund.

Helen Branswell

Helen Branswell covers issues broadly related to infectious diseases, including outbreaks, preparedness, research, and vaccine development. Follow her on Mastodon and Bluesky .

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CDC Confirms Human H5 Bird Flu Case in Missouri

September 6, 2024 -- CDC has confirmed a human case of avian influenza A(H5) ("H5 bird flu") reported by the state of Missouri. The case was identified through that state's seasonal flu surveillance system. The specimen was forwarded to CDC for confirmatory testing per usual protocols and confirmed yesterday. An investigation into the potential exposure is ongoing by the Missouri Department of Health and Senior Services (DHSS).

Case Information

Missouri DHSS reports that the patient, who was hospitalized, had underlying medical conditions, was treated with influenza antiviral medications, subsequently discharged, and has recovered. There is no immediate known animal exposure. No ongoing transmission among close contacts or otherwise has been identified.

This is the 14 th human case of H5 reported in the United States during 2024 and the first case of H5 without a known occupational exposure to sick or infected animals. H5 outbreaks in cattle have not been reported in Missouri, but outbreaks of H5 have been reported in commercial and backyard poultry flocks in 2024. H5N1 bird flu has been detected in wild birds in that state in the past.

While other novel flu cases have been detected through the country's national flu surveillance system, this is the first time that system has detected a case of H5. Targeted H5-outbreak specific surveillance has been conducted as part of ongoing animal outbreaks and has identified all the other cases. In this case, the specimen from the patient originally tested positive for flu A, but negative for seasonal flu A virus subtypes. That finding triggers additional testing.

CDC continues to closely monitor available data from influenza surveillance systems , particularly in affected states, and there has been no sign of unusual influenza activity in people, including in Missouri.

Identification of the neuraminidase (the "N") in the patient specimen is pending further sequencing. Attempts to sequence the genome of the virus also are underway at CDC.

Based on available data, CDC's current assessment is that the risk to the general public from H5N1 remains low. CDC's recommendations related to H5 virus have not changed at this time. As always, circumstances may change quickly as more information is learned. The results of this investigation will be particularly important in light of the current lack of an obvious animal exposure. It is important to note that, while rare, there have been novel influenza A cases where an animal source cannot be identified. The main concern in these situations is that no onward transmission is occurring. Findings from the ongoing investigation will inform whether guidance changes are needed.

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