Biomedical experimentation on animals

Biomedical experimentation on animals

Biomedical experimentation dates back many years. Early experimentation included blood transfusions, vivisection (surgical procedures performed on conscious, living animals), and dissection of apes, dogs, and pigs. In present times testing on nonhuman animals is obligatory in codes of ethics for biomedical research. According to the Nuremberg Code adopted in 1947, any experiments carried out on human beings should be “designed and based on the results of animal research.”1 The Helsinki Declaration, adopted in 1964 by the 13th World Medical Assembly, also notes that medical research on human subjects “should be based on laboratory and animal experiments or other scientifically established facts.”2

Since 1940 there has been a new specialty in veterinary medicine: “laboratory animal science.” This makes clear the central role given to the use of animals in research, to the point of being a true paradigm.

There are several different purposes for which animals are used and killed in the field of biomedical research, including the following:

Study of disease

A number of procedures are aimed at studying how different diseases evolve. This is done by deliberately giving animals the disease that is being studied so as to observe how the disease and treatments might work in humans. A wide range of diseases are studied in this manner, such as digestive, neurological and genetic diseases. Animals are also used to study brain injury, spinal cord injury, Parkinson’s, AIDS, cancer, obesity, and many others. In order for these experiments to be carried out, animals are forced to endure terrible diseases, traumatic injury, force-feeding, burns, social deprivation, and exposure to toxic substances.

Development of new drugs

The discovery of new medicines generally involves four main steps:

1. Identification of potential drugs. First, new chemicals that may be useful as medicines are identified. The number of animals used in experiments during this phase makes up around 10% of the total number of animals who are used in the process of creating new medicines.

2. Testing new substances. Substances that are considered promising then go through further tests. This is by far the area in which the most animals are experimented on in the process of creating new medicines. Up to 80% of animals who are tested are used in this phase.

3. Safety testing. The safety of substances selected from the previous phase are then further tested. Generally more than 10% of the animals who are tested are used in this phase.

4. Refinement of the final product. The final phase in the development of new medicines involves studies on humans. In general, nonhuman animals are not experimented on at this point.3

For a single drug, up to 3,000 animals may be used in various tests. Pain for these animals could often be controlled with medicine, but the medicines might interfere with the experiment. This is one reason why pain medication may not be given. In addition, experimenters may significantly prolong the suffering of animals by keeping them alive for a long time after they are fatally harmed by the experiments. Researchers keep these animals alive only because the death of animals during experiments may make the data less useful.

Animals used for experimentation

A wide variety of animals are used in research. They include the following:

Mice and rats. Mice and rats are used for a large number of purposes. They are commonly subjected to experiments on the reaction of mammals to an attack, intoxication, or experimental infection (parasitic, bacterial, or viral) and immunological, oncological (relating to tumors), teratological (abnormal physiological development), and embryological reactions and disorders. Mice are the animals most often used for analysis of human illnesses of genetic origin. Rats are also frequently used in nutritional, behavioral, and endocrinological studies. Mice and rats are used in experiments on cancer and nutrition, kidney disease, cholesterol and skin transplantation as well as many others.

Dogs and cats. Dogs are often used to study cardiovascular issues, CPR techniques, anemia, heart disease, and many other issues. Cats are commonly experimented on to study neurological diseases, cancer, genetic issues and also in studies of the immune system, among many others.

Rabbits. Rabbits are used to test the safety of drugs and vaccines, as well as to study transplants, cholesterol, product safety, and many other things that are mainly used in the production of antidotes, pharmacology, toxicology, teratogenicity, and reproduction.

Guinea pigs. Guinea pigs are used as models in immunological, pharmacological, and nutritional studies.

Hamsters. Hamsters are used for several purposes, including reproduction, cytogenesis, and immunology studies.

Birds, reptiles and frogs. Birds, reptiles and frogs are used in experiments involving diabetes, liver cancer, neurobiological issues and in many other experiments.

Cows. Cows are used in tests involving organ transplants, diabetes and heart disease, among others.

Primates. Primates are used in research on the subject of AIDS, Parkinson’s, anaesthesia, measles and many other diseases.

Most animals used by researchers have been bred specifically to be the subjects of experiments. However, other animals who are experimented on may be obtained from places such as shelters or by placing or answering ads. In many cases the animals are genetically modified, and the genetic modifications may cause them considerable suffering during their lives. Early death may also result due to some genetic modifications.

Examples of procedures

Below are just a few descriptions of the types of experiments and conditions4 that animals are used in:

Tests for skin-sensitization. Guinea pigs are often used for this. Several doses of a chemical are placed on the skin of the guinea pig to see if a subsequent application causes a greater immune reaction than it does on the skin of a guinea pig who has not been previously exposed to the substance.

Tests on carcinogenicity. Animals such as rats are dosed with potentially carcinogenic substances for as long as two years and the tumors that grow are then studied. In other experiments, pregnant rabbits are dosed with a chemical during their entire pregnancy and their uterine contents are then studied to see if fetal death or altered growth occurred because of these chemicals.

Tests on heart conditions. Conditions such as heart attacks and strokes are induced artificially in dogs so they can be studied.

Paralysis tests. To create paralysis and spinal cord injuries, weights are dropped onto rodents.

Nausea tests. Electrodes are implanted in the intestines of dogs to make them vomit.

Headache tests. Migraine-like symptoms are artificially created in primates by using specific chemicals.

Toxicity tests. These tests assess, as their name suggests, the extent to which certain substances can be toxic. Some of these tests may cause the skin of the animals to crack and peel. Toxicity tests can also cause internal bleeding, vomiting, convulsions, and coma.

Metabolic studies. Animals have tubes implanted in their bile ducts.

Histocompatibility tests. In past histocompatibility tests, new materials were always evaluated on humans to see if they were biocompatible. Some time ago, this became unacceptable. Now, for a material to be considered biocompatible, it must pass through several stages. These are in vitro testing, in vivo testing (it is here that animals are used rather than humans), and in-use tests.

Medications. Animals are also used for bioavailability studies, which is research on the level or frequency with which a medicine or drug is absorbed or made available in body tissues or organs after having been administered.

Pathogenesis research. Transgenic animals are used in research on pathogenic mechanisms of illnesses as testing instruments for possible therapeutic compounds, and as in vivo instruments of validation for potential treatments.

Neurobiology. Animals, especially rats, are used to study the effects of surgery and nutrition on the brain.

The debate on animal experimentation

Defenders of animal experimentation claim that even though methods that do not harm animals may be developed, there are still a number of cases in which it is necessary to try drugs or procedures in living animals. Those opposing this view have argued that experiments on animals may not accurately reflect the effects these drugs will have in humans. Differences due to the species and breed of the animals used may cause the results to inaccurately predict effects in humans. Other problems can arise from the population of animals used being rather homogenous, whereas the population of humans is quite diverse. Differences between the way the tested materials are administered in the laboratory and the way they are ingested or absorbed by humans may also make the results inaccurate.5

They further argue that even though humans and nonhuman animals may in many cases develop similar health problems, the physiological mechanisms are different. This would be the reason, they argue, why extrapolating data from animal experiments is not epistemologically sound.6

Apart from these criticisms, and regardless of whether they are right or not, it can be pointed out that there is a sharp contrast between the ways humans and nonhuman animals are considered when it comes to biomedical research. We will see this in the following two sections.

Regulations are not making a difference

In a number of countries, there exist some regulations having to do with how animals can be used in experiments. However, these regulations, where they exist, commonly impose very few limitations on the use of nonhuman animals.

In the European Union, while animal experimentation for cosmetics is prohibited, experiments with scientific aims rarely prohibit the use of animals. The main current regulation in the EU is the Directive 2010/63/EU on the protection of animals used for scientific purposes.7 Though it shows less disregard for nonhuman animals than virtually any other piece of regulation in this field, it does not question animal experimentation itself. It stipulates some requirements aimed at reducing the suffering endured by animals, but these can be outweighed by the requirements of the experiment, and it does not consider that the lives of animals are worthy of being preserved and protected. This is shown not only by the fact that animals are routinely killed in procedures, but also by the large numbers of animals who are killed simply because they were bred to be used in experiments but were not. They are killed anyway, and not only is this not prohibited, it is standard practice.

In the USA, animal experimentation is meant to be carried out in accordance with what the Animal Welfare Act of 1966 stipulates.8 Despite the advances in our understanding of animal sentience and the arguments regarding the moral consideration of animals in recent decades, a law that is around half a century old still applies and has not been replaced by new legislation that provides far more significant protection to animals. To understand how poorly the Animal Welfare Act can provide any defense to animals, it is important to note that it excludes from its consideration animals such as rodents, which are the overwhelming majority of animals used in experimentation.

The enforcement of the Animal Welfare Act is assigned to the Animal Care division of the Animal and Plant Health Inspection Service (APHIS), which is a branch of the United States Department of Agriculture (USDA). This is not an animal protection body, but one that fully accepts the harm animals endure for human benefit.

It is similar in Canada, where animal experiments are meant to be carried out in accordance with the Canadian Council on Animal Care (CCAC) guiding principles.

In other countries such as Australia and Brazil, Animal Ethics Committees are the ones that can determine whether a certain procedure using nonhuman animals can be accepted or not. These committees commonly include supporters of experimentation, who are almost always their majority. Procedures are commonly accepted even if they cause significant harm to animals.

Finally, in some countries such as Japan, while there is a Law for Humane Treatment and Management of Animals,9 in practice this is not meaningful at all, since there is no enforcement and there are no third-party agencies required to monitor what is done to the animals. It is assumed that experimenters will self-regulate, which is tantamount to having no regulation whatsoever.

All of this shows that animals used in biomedical testing will continue to have virtually no protection as long as laws accept that their lives and wellbeing have little value.

Animal ethics and experimentation

There are certain purposes for which the benefits of testing on nonhuman animals clearly do not outweigh the harms, because the harms are very significant in relation to trivial benefits (for example, cosmetics testing). In other cases the benefits are greater and may outweigh the harms caused to the victims. Today different ethical theories exist with different conceptions of the criteria we should use in making decisions that affect testing subjects – human and nonhuman.10 According to some theories, causing harm to an individual to benefit others is always morally unacceptable, so they would forbid experiments in these cases. According to other theories, we should instead consider the harms caused to some individuals alongside the benefits it gives to others, and give priority to the one that carries more weight. According to these views, experimentation in the latter cases would be acceptable. But as long as those defending this view do not apply it to humans but only to nonhuman animals they are displaying a speciesist bias and are not really accepting that ethical view consistently. In fact the question of the usefulness of in-use or clinical testing is rarely looked at from the benefits vs. harm perspective. It is simply assumed that nonhuman animals can be used as resources if it benefits humans. Speciesism should be rejected though: we must make our ethical evaluations of every practice by setting aside the species to which those involved belong, and considering only the interests they all have.

Further readings

Animal Procedures Committee (2003) Review of cost-benefit assessment in the use of animals in research, London: Home Office.

Baird, R. M. & Rosenbaum, S. E. (eds.) (1991) Animal experimentation: The moral issues, New York: Prometheus.

Balls, M. (1994) “Replacement of animal procedures: Alternatives in research, education and testing”, Lab Animal, 28, pp. 193-211.

Bockamp, E.; Maringer, M.; Spangeberg, C.; Fees, S.; Fraser, S.; Eshkind, L.; Oesch, F. & Zabel, B. (2002) “Of mice and models: Improved animal models for biomedical research”, Physiological Genomics, 11, pp. 115-132.

Bluemel, J.; Korte, S.; Schenck, E. & Weinbauer, G. (eds.) (2015) The nonhuman primate in nonclinical drug development and safety assessment, Amsterdam: Academic Press.

Caplan, A. L. (1983) “Beastly conduct: Ethical issues in animal experimentation”, Annals of the New York Academy of Sciences, 406, pp. 159-169.

Chader, G. G. (2002) “Animal models in research on retinal degenerations: Past progress and future hope”, Vision Research, 42, pp. 393-399 [accessed on 18 October 2013].

Cothran, H. (ed.) (2002) Animal experimentation: Opposing viewpoints, San Diego: Greenhaven.

DeGrazia, D. (1999) “The ethics of animal research: What are the prospects for agreement?”, Cambridge Quarterly of Healthcare Ethics, 8, pp. 23-34.

European Commission (2013) Seventh report on the statistics on the number of animals used for experimental and other scientific purposes in the member states of the European Union, Brussels: European Commission [accessed on 2 September 2016].

European Science Foundation Policy Briefing (2001) The use of animals in research, 2nd ed., Strasbourg: European Science Foundation.

Frey, R. G. & Paton, W. (1989) “Vivisection, morals and medicine: An exchange”, in Regan, T. & Singer, P. (eds.) Animal rights and human obligations, Englewood Cliffs: Prentice Hall, pp. 223-226.

Gavin, S. L. & Herzog, H. A. (1992) “The ethical judgment of animal research”, Ethics & Behavior, 2, pp. 263-286.

Górska, P. (2000) “Principles in laboratory animal research for experimental purposes”, Medical Science Monitor, 6, pp. 171-180 [accessed on 22 June 2023].

Guillen, J. (ed.) (2013) Laboratory animals: Regulations and recommendations for global collaborative research, San Diego: Academic Press.

Kirk, A. D. (2003) “Crossing the bridge: Large animal models in translational transplantation research”, Immunological Reviews, 196, pp. 176-196.

Langley, G. (ed.) (1990) Animal experimentation: The consensus changes, London: MacMillan.

Matsuda, Y. (2004) “Recent trends in the number of laboratory animals used in Japan”, ATLA: Alternatives to Laboratory Animals, 32, suppl. 1A, pp. 299-301.

Ninomiya, H. & Inomata, T. (1998) “Current uses of laboratory animals in Japan and alternative methods in research, testing and education”, Applied Animal Behaviour Science, 59, pp. 219-25.

Orlans, F. B. (1998) “History and ethical regulation of animal experimentation: An international perspective”, in Kuhse, H. & Singer, P. A companion to bioethics, Oxford: Blackwell, pp. 399-410.

Rice, M. J. (2011) “The institutional review board is an impediment to human research: The result is more animal-based research”, Philosophy, Ethics, and Humanities in Medicine, 6.

Rowan, A. N. (1984) Of mice, models and men: A critical evaluation of animal research, Albany: State University of New York Press.

Russell, W. M. S. & Burch, R. L. (1959) The principles of humane experimental technique, London: Methuen.

Swart, J. A. A. (2004) “The wild animal as a research animal”, Journal of Agricultural and Environmental Ethics, 17, pp. 181-197.

Tannenbaum, J. & Rowan, A. N. (1985) “Rethinking the morality of animal research”, Hastings Center Report, 15 (5), pp. 32-43 [accessed on 22 September 2012].


1 Nuremberg Military Tribunals (1946-1949) Trials of war criminals before the Nuernberg Military Tribunals under Control Council Law no. 10, Washington, D. C.: U. S. Government Printing Office.

2 World Medical Association (1964) Declaration of Helsinki: Recommendations guiding doctors in clinical research, Helsinki: 18th WMA General Assembly [accessed on 30 October 2020].

3 See Nuffield Council on Bioethics (2005) The ethics of research involving animals, London: Nuffield Council on Bioethics, pp. 135-157 [accessed on 25 June 2020].

4 Botham, P. A.; Basketter, D. A.; Maurer, T.; Mueller, D.; Potokar, M. & Bontinck, W. J. (1991) “Skin sensitization—a critical review of predictive test methods in animals and man”, Food and Chemical Toxicology, 29, pp. 275-286. Lang, C. M. (2009) “The cost of animal research”, Lab Animal, 38, pp. 335-338. Royal Society (2004) The use of non-human animals in research: A guide for scientists, London: The Royal Society. MORI (2002) The use of animals in medical research study, conducted for the Coalition of Medical Progress, March – May 2002, London: MORI. Monamy, V. (2009 [2000]) Animal experimentation: A guide to the issues, 2nd ed., Cambridge University Press. Orlans, F. B. (1993) In the name of science: Issues in responsible animal experimentation, Oxford: Oxford University Press. Chow, P. K.; Ng, R. T. & Ogden, B. E. (2008) Using animal models in biomedical research: A primer for the investigator, Singapore: World Scientific. Committee to Update Science, Medicine, and Animals; Institute for Laboratory Animal Research; Division on Earth and Life Studies & National Research Council (2004) Science, medicine, and animals, Washington, D. C.: National Academies Press.

5 See for instance Sharpe, R. (1994) Science on trial: The human cost of animal experiments, Sheffield: Awareness Books; Croce, P. (1999) Vivisection or science: An investigation into testing drugs and safeguarding health, 2nd ed., New York: Zed. See also: Greek, J. S. & Greek, R. (2000) Sacred cows and golden geese: The human cost of experiments on animals, New York: Continuum; (2003) Specious science: Why experiments on animals harm humans, New York: Bloomsbury Academic.

6 See LaFollette, H. & Shanks, N. (1997) Brute science: Dilemmas of animal experimentation, New York: Routledge; Shanks, N. & Greek, C. R (2009) Animal models in light of evolution, Boca Raton: Brown Walker.

7 European Parliament & Council of the European Union (2010) “Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes”, Official Journal of the European Union, 20.10.2010, pp. L. 276/33-79 [accessed on 12 February 2014].

8 National Agricultural Library (2013 [1966]) Animal Welfare Act, Washington, D. C.: National Agricultural Agriculture [accessed on 11 April 2021].

9 Shoji, K. (2008) “Japanese concept and government policy on animal welfare and animal experiments”, Alternatives to Animal Testing and Experimentation, 14, pp. 179-181. Takahashi-Omoe, H. & Omoe, K. (2007) “Animal experimentation in Japan: Regulatory processes and application for microbiological studies”, Comparative immunology, microbiology and infectious diseases, 30, pp. 225-246.

10 VanDeVeer, D. & Regan, T. (eds.) (1987) Health care ethics: An introduction, Philadelphia: Temple University Press. Clune, A. C. (1996) “Biomedical testing on nonhuman animals: An attempt at a ‘rapprochement’ between utilitarianism and theories of inherent value”, The Monist, 79, pp. 230-246. Singer, P. (1996) “Ethics and the limits of scientific freedom”, The Monist, 79, pp. 218-229.