animals in research

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animals in research Animals are widely used in the biomedical sciences, for purposes ranging from studying the functions of human and animal bodies and the nature of disease, to toxicological testing to assess the safety of both medical and non-medical products. Their use in science has a long and well-documented history, as has the philosophical debate over such use (see, for example, Vivisection in Historical Perspective, edited by N. A. Rupke). A few points will be mentioned briefly here to put this in context with the present day situation.

Animal experiments were described in ancient Greece and Rome. The author of the Hippocratic text (around 350 bc), for example, describes cutting the throat of pigs to observe the mechanism of swallowing. Galen, (129–216 ad) the most renowned physician of the Hellenic period, used pigs to demonstrate the effects of severance of various nerves. Even toxicity tests were performed by King Mithridates of Persia (132–63 ad) on both humans and animals to learn more about poisons and their antidotes.

The disciplines of anatomy and physiology were keenly pursued from the Renaissance period onwards, with studies largely based on the dissection of living animals. Some of the most influential figures during this period were Andreas Vesalius (1514–64), who dissected monkeys, pigs, and goats; William Harvey (1578–1657), well known for his discovery of the circulation of the blood through live dissection; and René Descartes (1596–1650), the French scientist/philosopher.

From the mid-1880s science, and particularly physiology, increasingly used animal experimentation as a major ‘tool’. The French physiologist Francois Magendie (1783–1855) and his pupil Claude Bernard (1813–78) performed thousands of experiments on animals, with Bernard subsequently becoming known as the ‘father of modern medicine’. These early experiments on animals caused great suffering. Either there were no anaesthetics, or they were not used, so living, conscious animals were cut up (literally vivisected) with no consideration for what they experienced in terms of pain or suffering. Descartes, in fact, expressed the view that animals were like machines and did not feel ‘real’ pain, and that their lack of rational awareness meant that such pain was morally unimportant.

As interest in science and medicine developed, so the use of animals became an integral part of the research method in many scientific disciplines. It remains so as we have moved into the twenty-first century. The developing scientific use of animals, however, has been accompanied by doubts and concerns, both about the morality of such use (particularly once more was learned about animals and their ability to suffer) and the validity of experiments with regard to the information they provided and its application to human medicine. Until the second half of the eighteenth century, proponents of such views came mainly from the disciplines of philosophy and the arts and, to a lesser extent, the sciences. However, after this time ‘vivisection’ entered into both public and political debate, at first in the UK, much later elsewhere. The use of animals in experiments is now one of the most contentious issues of debate within the public arena.

Legislative controls

Until the nineteenth century there were no controls anywhere in the world on what could be done to animals in experiments, other than that exerted by the moral consciousness of the scientists themselves, or of their critics. However, once the issue became of public and political concern, legislation soon followed, and in 1876 the first law governing the use of animals in experiments — the Cruelty to Animals Act 1876 — was introduced in the UK. This Act applied to ‘experiments calculated to give pain to vertebrates’. It established the Home Office as the controlling authority and required premises where experiments were carried out to be registered and subject to ‘random and unannounced inspection by Home Office Inspectors’. Individual researchers had to be licenced and provide an Annual Return of the numbers of experiments performed under the Act. A special certificate was required to work on cats, dogs, horses, or mules, reflecting additional public concern about such animals. This legislation remained in force until 1986, when it was replaced with the more stringent Animals (Scientific Procedures) Act 1986 (ASPA). There are now at least 20 countries worldwide with legislation regulating experiments on animals.

The UK Animals (Scientific Procedures) Act 1986 — how it operates.

The ASPA regulates ‘any experimental or other scientific procedures applied to a protected animal which may have the effect of causing that animal pain, suffering, distress or lasting harm’. It covers all vertebrate species and one invertebrate, Octopus vulgaris. Mammals and birds are covered from halfway through their gestation or incubation period; fish and amphibians from the time at which they become capable of independent feeding.

The Act is based on a three-tier licensing system, administered by the Home Office through a team of Inspectors qualified in medicine or veterinary science. The establishment where procedures on animals are carried out must have a licence (the Certificate of Designation), as must the research project (the Project licence), and the individuals carrying out experiments or procedures (the Personal licence).

Further provisions include the need for two people to be appointed at each establishment (the Named Veterinary Surgeon and the Named Animal Care and Welfare Officer) who have statutory responsibility for overseeing the animals' health and daily care. The person who has overall responsibility for the establishment itself is appointed as the Certificate Holder.

Standards of animal husbandry and care are defined in Home Office Codes of Practice issued under the Act. These represent minimum standards — although they are often wrongly interpreted as providing guidelines on best practice.

There is also the provision for a statutory committee (the Animal Procedures Committee (APC)) to provide independent advice to the Secretary of State about matters of particular concern relating to the Act; the use of animals for testing cosmetics and the use of primates, for example. There are currently 24 members of the APC, drawn from various disciplines including science, animal protection, philosophy, and law.

The ASPA requires that a certain amount of information be made available within the public domain. Each year the Home Office collects and publishes statistics on the numbers and species of animals used. A limited amount of information on the purposes for which animals are used is also published, including categorization of the scientific disciplines (e.g. immunology, physiology, microbiology) and whether or not the use was to satisfy a national or international regulatory requirement (for example regarding the safety assessment of chemicals). In addition a summary of the work of the APC is made public through the Committee's annual report. This information, though welcome, is insufficient to gain a full understanding of what is done to animals, the reason for animal use, and the amount they suffer in the name of science. Nevertheless, the UK is the only country to provide this level of information.

Facts and figures from the Home Office statistics.

Types of animal used in research and testing

Animals are used as ‘models’ of humans and/or of other animals in a wide range of scientific disciplines. In broad terms these relate to: the study and treatment of human and animal diseases and disorders, gaining fundamental knowledge in the biological sciences, and the assessment of the safety (or level of risk) of chemicals and non-medical products such as pesticides, agricultural chemicals, food additives, and household products. A considerable amount of animal use (about 80% in the case of dogs) is actually carried out to satisfy international regulatory laws or guidelines on the safety of human and veterinary medicines and other non-medical products. Other uses defined under the Act include breeding for genetic defects or modified genes, the diagnosis of disease, and in education and training. By far the greatest proportion of animals are used in fundamental and applied medical research.

Number of animals

The number of animals used annually in the UK is currently around 2.6 million. The figure world-wide has been estimated to be over 41 million, but it is impossible to be more accurate than this, since most countries do not collect detailed (or any) statistics.


The number of animals used in the UK has decreased steadily over the last 25 years. The numbers rose from the late 1940s when statistics were first recorded, reaching a peak of 5.5 million in 1971. The decrease in animal use results from a number of interrelated factors, including changing trends in scientific research, the high costs of using animals, and changes in attitudes to animals and their welfare in general.

The decrease in numbers levelled out in the mid-1990s, then in 1998 the UK statistics showed a slight rise. This was due to developments in genetic engineering with the use of genetically modified animals rising by 14% between 1998 and 1999. Genetic engineering is a rapidly developing science with applications in many different scientific disciplines, so this increase in animal use is likely to continue.

Species of animal

A wide range of vertebrate and invertebrate animal species are used in biomedical research, but only vertebrates, and one species of invertebrate (Octopus vulgaris), are regulated by the ASPA. Of vertebrates, by far the largest number used according to the most recent figures (for 1999) are mice and rats (63% and 21% respectively of the total). Birds accounted for 4%, fish for nearly 5%, guinea-pigs just over 2% and rabbits 1%. Dogs, cats and primates taken together accounted for about 0.3%; however, this still represents a lot of individual animals: 5933 dogs, 683 cats and 3191 primates. Other species of animals used include hamsters, gerbils, ferrets, horses, cattle, sheep, pigs, goats, reptiles, and amphibians.

In the UK most of the common laboratory species, including rodents, rabbits, dogs, cats, and primates, have to be bred specifically for research purposes and obtained from Government-licensed breeders and suppliers. Some (for example dogs, primates, and certain strains of genetically-engineered rodents) may be imported if they are not available in the UK, but this too requires Government licence.

Ethical issues

The philosophical arguments over the use of animals are well documented. In society as a whole there is a spectrum of views on whether animal experiments are acceptable. There is a controversial public debate encompassing arguments regarding the morality of using animals and the perceived scientific validity and potential benefit of animal experiments. At one end of the spectrum of views are those who consider all animal experiments to be immoral whether or not they can be shown to have benefit (to humans or other animals). At the other are those who consider few experiments to be unjustified if they benefit humans in any way. People express a variety of views within these extremes, depending on their overall view of the human–animal relationship, their understanding of the overall purpose of the work and its perceived benefit, the nature of the experiments, the amount of suffering caused, and the species of animal.

The use of animals in experiments undoubtedly presents a complex ethical dilemma. In medical research, for example, animals are used as ‘models’ of diseases that cause a considerable amount of human suffering. It is irrational to suppose that animals do not suffer similarly in such studies. Thus, there is clearly a conflict of interests between the individual animals who will suffer pain or distress and who are usually killed at the conclusion of the experiment, and the benefits of the research — whether these apply to medicine and science in general, the public, individual scientists, industry, or indeed other animals. From an animal welfare point of view, it is important for all those directly or indirectly involved with animal use, and who directly or indirectly benefit from it, to recognize this and to try to minimize the impact on animals.

One problem with how the debate is presented in public, particularly relating to the issue of the scientific validity of experiments, is that the arguments are usually put in absolute terms: it is stated that animal experiments have, or have not, contributed to medical advances. Selected examples are provided to support each view. But the situation is not that simple. Animals are used for many different purposes, not all of them intended to have a medical application (acquisition of knowledge is an acceptable benefit under ASPA), and each area of use has its particular scientific, animal welfare, and moral questions. The use of selective arguments can often mask, and thus prevent constructive discussion of, underlying issues of animal welfare and the need to critically assess the necessity and justification for individual animal experiments in practice.

How ethical views are interpreted and incorporated into the ASPA

The Act is utilitarian, in that it operates from the basic assumption that animal experiments can have benefit, and a benefit that justifies causing animals harm, which it then sets out to minimize and regulate. The fundamental ethical question of whether, and in what circumstances, an animal can be used for a scientific purpose is addressed by the ‘cost benefit’ assessment that must be carried out prior to granting a project licence. The costs to animals (the adverse effects) must be weighed against the potential benefits that are likely to result.

The definition of benefit under the Act is very wide and includes: protecting or improving human and animal health and safety, protecting the environment, and increasing scientific knowledge. The costs and benefits are set out in the project licence application, which is first assessed by the local Ethical Review Process (ERP) before being submitted to the Home Office Inspectorate for review on behalf of the Secretary of State. The system of local ethical review was introduced in 1999 to act as an adjunct to the Home Office Inspectorate in an attempt to improve implementation of the legislation. The aim is to provide a local framework ‘to ensure that all animal use in an establishment is carefully considered and justified and that proper account is taken of all opportunities for reduction, refinement and replacement’.

The costs to animals used to be interpreted as solely relating to the adverse effects of a procedure. However, it is increasingly recognized that the full costs for the animals are much greater, with the sourcing, transport, husbandry, handling and care, and euthanasia all contributing significantly to the overall impact on the animal. Primates, for example, may undergo journeys of up to 60 hours, and be housed in cages quite inappropriate to their social and behavioural needs, before they are even used in an experimental procedure, and this needs to be taken into account in any assessment of the justification for using them.

Ethics also have a practical component: as well as allowing decisions on whether an animal is used, they should also encompass consideration of how in practice animals are treated. In this context, reduction of animal suffering and improvement of welfare are duties both explicit and implicit in the Act, requiring adherence not only to the letter of the law, but also to its spirit. A major guiding principle is the ‘3Rs’ principle of humane experimental technique set out over 40 years ago by Russell and Burch. They believed that humane experimental technique was integral to good science. They proposed that scientists should wherever possible replace animals with humane alternatives, reduce the number of animals in an experiment to a minimum consistent with obtaining good statistical data, and refine techniques to minimize suffering. The provision of husbandry systems that meet both the behavioural and the physiological needs of the animals is another practical consideration that should be given high priority alongside the scientific objective of the project. The 3Rs are now widely accepted as a means not only of reducing the impact of experiments on animals but also of improving the quality of the science. Indeed, UK and EU legislation requires scientists to use alternatives to living animals if available.

Difficult decision

The cost–benefit assessment is widely claimed to ensure that animals are only used when there will be a ‘benefit’ which is ‘necessary and justified’. However, necessity and justification are subjective concepts, as too is benefit, and all can be interpreted in very different ways by different people, at different times, in different situations, cultures, and contexts. In practice it is difficult to know how to weigh such disparate units as a known harm versus a potential benefit. In recognition of this, there have been several ethical schemes developed to try to help people think through the factors which are important in making their judgements.

The introduction of the Ethical Review Process will widen the review of projects to include more members of each establishment that carries out animal experiments. There is also provision for including ‘lay’ members in the process, and this will be an evolving concept in the coming years.

In conclusion

The prevailing view within the biomedical sciences is that animal research has led to medical and veterinary advances and will continue to do so. However, this use of animals leads to a serious conflict between the needs of laboratory animals and those of humans and other animals, with all the attendant moral and ethical dilemmas that this entails.

The use of animals in experiments is a privilege not a right, and the necessity and justification for using them should always be critically evaluated on a case by case basis. Care and consideration for animals should be a basic principle within science. There needs to be a proactive approach, which should go beyond the bare minimum legal requirements, giving animals and their welfare high priority. Where animals continue to be used, the aim should always be to minimize that use, to minimize or avoid harms to animals, to maximize the potential benefits of the research, and to ensure that these benefits are applied in practice.

Maggy Jennings


Regan, T. and and Singer, P. (1989). Animal rights and human obligations, (2nd edn). Prentice Hall, New Jersey.
Rupke, N. A. (ed.) (1987). Vivisection in historical perspective. Croom Helm, US.
Russell, W. M. S. and and Burch, R. L. (1959). The principles of humane experimental technique. Methuen, London.
Smith, J. A. and Boyd, K. M. (eds) (1991). Lives in the balance: the ethics of using animals in research. Oxford University Press, Oxford.