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National Research Council (US) and Institute of Medicine (US) Committee on the Use of Laboratory Animals in Biomedical and Behavioral Research. Use of Laboratory Animals in Biomedical and Behavioral Research. Washington (DC): National Academies Press (US); 1988.

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Use of Laboratory Animals in Biomedical and Behavioral Research.

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2Patterns of Animal Use

Animals are used for a variety of purposes in the United States—for food and other products; in sports and entertainment; for companionship; for the production of enzymes, hormones, and other biological products; and in research, testing, and education. The largest use of animals is in food and fiber production, accounting for over 5 billion vertebrates each year (U.S. Department of Agriculture, 1985). An estimated 110 million dogs and cats are household pets in the United States. Between 17 million and 22 million animals are estimated to be used annually in the United States in research, education, and testing. About 85 percent of these are rats and mice, and less than 2 percent are cats, dogs, and nonhuman primates (Office of Technology Assessment, 1986).

Animals are used in research to improve the health and welfare of humans and animals and to gain basic knowledge that cannot be gained in other ways. Research conducted on animals varies widely in its impact on the animal subjects themselves. One field of behavioral research consists of observations of animals living in colonies that simulate their natural environments but with adequate food supplies and no predators. In some research projects, animals are subjected to experimental procedures and then receive supportive care, because their long-term survival and the validation of methods are the goals of treatment (examples include the development of organ transplantation and chronic toxicology). Some research animals are subjected to toxic substances and painful procedures until they are disabled or die, as when determining the lethal dose of radiation used in cancer therapy. Some are killed to obtain an essential organ, such as the liver, to be used in further studies. Others are anesthetized, subjected to an experimental procedure, and killed without regaining consciousness.

Not only is there considerable variation in how animals are used, but there is variation in how many and what types of animals are used in experiments.

Numbers of Animals Used

In 1952 the National Research Council established the Institute for Laboratory Animal Resources (ILAR) to serve as a coordinating agency and an information resource on the use of laboratory animals. In 1962, 1968, and 1978, ILAR conducted major surveys of laboratory animal facilities and resources, with the results of the 1978 survey being published by the U.S. Department of Health and Human Services (National Research Council, 1980). The 1968 and 1978 ILAR surveys included most of the entities that use animals in biomedical research, including nonprofit, commercial, military, and federal organizations. ILAR is currently planning a fourth survey.

The Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA) also collects data on the extent of animal use. Each year APHIS prepares an Animal Welfare Enforcement Report, which summarizes the annual reports filed with APHIS by registered research facilities that use animals in research (U.S. Department of Agriculture, 1972–1987). All registered research facilities are required to submit these reports. Institutions are not required to report on their use of rats, mice, birds, and domestic farm animals used for research, but the annual report form has space for voluntary reporting on the use of rats and mice.

Table 1 summarizes information from the ILAR and APHIS surveys and from estimates prepared by Health Designs, Inc., for the Office of Technology Assessment (1986). As demonstrated by the table, data from various sources show a lack of consistency. It should be noted that a considerable decrease was observed between 1967 and 1978 in the numbers of animals used as measured by ILAR. Recent annual reports from APHIS, however, have shown that the total number of animals used in experimentation (excluding rats, mice, birds, and wild animals) increased from 1,571,693 in 1983 to 1,633,933 in 1986 (U.S. Department of Agriculture, 1972–1987). The Office of Technology Assessment (1986), in evaluating all the data, has concluded that the available data are too imprecise to allow any conclusions to be made regarding recent trends in overall animal use. The ILAR survey being planned will provide more current information on animal use.

TABLE 1. Various Estimates of the Number of Animals Used in the United States.


Various Estimates of the Number of Animals Used in the United States.

Use of Animals in Research by the Federal Government

The federal government is a major user of research animals. Specifically, the following departments and agencies use animals for intramural research and testing (Office of Technology Assessment, 1986).

  • The U.S. Department of Agriculture conducts research with animals to improve animal health and the quality of animal products, such as food and fiber.
  • The U.S. Department of Defense conducts experimental research in a wide variety of areas, with animals being used by the Air Force, the Army, the Navy, the Uniformed Services University of the Health Sciences, the Defense Nuclear Agency, and the Armed Forces Institute of Pathology.
  • The U.S. Department of Energy conducts research on the health and environmental effects of energy technologies and programs. Most of this research takes place at the privately managed national laboratories—such as Brookhaven National Laboratory, Oak Ridge National Laboratory, and the Pacific Northwest Laboratories—and through contracts and grants to scientists employed at universities and other research facilities.
  • The U.S. Department of Health and Human Services carries out intramural animal research or testing within four of its components: the National Institutes of Health (NIH); the Food and Drug Administration (FDA); the National Institute on Drug Abuse (NIDA), which is part of the Alcohol, Drug Abuse, and Mental Health Administration (ADAMHA); and the National Institute for Occupational Safety and Health (NIOSH), which is part of the Centers for Disease Control. NIH is the largest of these four components and uses more animals than any other federal department or agency.
  • The U.S. Department of the Interior, in cooperation with state and private organizations, conducts research and education programs to improve fish and wildlife resource management.
  • The U.S. Department of Transportation conducts research on transportation safety using animals under the authority of the Hazardous Transportation Act of 1974 and the National Traffic and Motor Vehicle Safety Act of 1966.
  • The Consumer Product Safety Commission (CPSC) conducts tests to determine the toxic potential of consumer products.
  • The Environmental Protection Agency (EPA) performs research involving animals under the statutory and regulatory authority of the Toxic Substances Control Act and the Federal. Insecticide, Fungicide, and Rodenticide Act.
  • The National Aeronautics and Space Administration (NASA) conducts research with animals to acquire knowledge that can be used to protect the health of astronauts, both during their missions in space and after their return to earth.
  • The Veterans Administration (VA) uses animals in its research and development divisions and in its education programs.

The Office of Technology Assessment (1986) has estimated that the total federal use of animals in 1983 was 1.6 million, with about 90 percent of these animals being rats and mice.

Use of Animals in Education

The number of animals used in education is unknown, but most observers think that it is relatively small. For example, an estimated 53,000 animals are used annually for teaching in medical and veterinary schools (Office of Technology Assessment, 1986). However, animal use in high schools and colleges might be most people's only contact with laboratory animals, making it an important determinant of how the public feels about such use. This topic is outside the charge of the committee, but the recent report by the Office of Technology Assessment (1986) examines the issue in some detail.

Use of Animals in Testing

Animals are used extensively to test the safety and efficacy of compounds produced by the chemical, cosmetic, and drug industries. The use of so many animals, particularly rats and mice, in testing cannot be ignored even though the committee was charged primarily with looking at the use of animals in research. Government regulatory agencies, such as FDA, EPA, CPSC, and the Occupational Safety and Health Administration (OSHA), often explicitly require the use of animals in testing. A list of some commonly used tests follows (Office of Technology Assessment, 1986). Descriptions of possible alternative methods can be found in Chapter 4.

  • Acute toxicity tests consist of single doses at concentrations high enough to produce toxic effects or death. They are often used to screen substances for relative toxicity. The LD50, which is the dose of a test substance at which half the test animals can be expected to die, is one such test.
  • Eye and skin irritation tests, which usually consist of a single exposure, are generally used to develop warnings for handling and to predict the toxicity of accidental exposure. The most common method used to test eye irritation is the Draize test, in which a test substance is applied to one eye of an adult rabbit, with the untreated eye serving as a control (Draize et al., 1944).
  • Repeated-dose chronic toxicity tests entail repeated exposures to substances for periods of two weeks to more than a year to determine the possible effects of long-term exposure. Rats are most commonly used for these tests.
  • Carcinogenicity tests involve repeated exposures to substances for most of an animal's lifespan to detect possible human carcinogens.
  • Developmental and reproductive toxicity tests consist of a variety of procedures to determine the potential of foreign substances to cause infertility, miscarriages, and birth defects. Rats and rabbits are the most commonly used animal subjects.
  • Neurotoxicity tests use a variety of doses and exposures to determine toxic effects on the nervous system. Toxic end points include behavioral changes, lack of coordination, motor disorders, and learning disabilities in animals.
  • Mutagenicity tests include a variety of methods for determining whether genetic material of germ or somatic cells has been changed.
  • Biological screening tests investigate the biological activity of organic compounds. Animals may be used in these tests depending on the type of biological activity being investigated.

Most of the above-mentioned tests require the use of large numbers of animals. However, as mentioned earlier, the number of animals used in testing is not known. Most testing is thought to be conducted in private commercial establishments that use primarily rats and mice, which under current regulations are not subject to the reporting requirements of the Animal Welfare Act. A recent estimate of the total number of animals used in testing was ''several'' million (Office of Technology Assessment, 1986). Another report (Theta Corporation, 1986) estimated that the use of animals in testing and industrial research is considerably greater than that, with organizations outside of government and academia accounting for over 75 percent of the estimated 22 million laboratory animals used annually. Of these animals, rodents by far are used in the greatest numbers.

New Technologies and Future Laboratory Use of Animals

The new and rapidly expanding field of biotechnology will have an impact on the species and numbers of laboratory animals used, but it is too early to predict precisely its ultimate effects. In some cases, the number of animals used might be reduced as biotechnology provides new testing methods acceptable to governmental regulatory authorities. In other cases, biotechnology might cause a need for more animals as well as shifts in the relative numbers of various species of animals used. At present, the biotechnology industry in the United States purchases an estimated 11 percent of all laboratory rodents sold, about 5 percent of the swine, and about 2 percent of the rabbits and dogs, but few primates or cats (Theta Corporation, 1986).

Several effects of biotechnology can already be seen. Rabies virus is widely distributed in nature. It was initially studied by infecting live laboratory animals with the virus, which led to vaccines produced using live animals. Recently, new diagnostic tests have been developed that use monoclonal antibodies produced by cell cultures, and vaccines are being produced with recombinant DNA technology (Freiherr, 1986). These changes have greatly reduced the use of animals for this purpose.

Proteins such as growth hormone and insulin can now be made using bioengineering techniques. Although this method of production will not eliminate the use of animals, it may reduce the number used per product, because safety tests can then be performed with larger batches of a uniform product.

The increasing sophistication in determining molecular structure and using it to predict biochemical function may reduce the use of animals. Scientists can use advances in technology to determine the active sites of molecules and even the attachment sites of viruses.

Such information may permit drug synthesis to proceed in a more directed fashion. New compounds developed in this way will still require safety and efficacy testing in animals. Animals will also still be needed for the validation of predicted results.

The numbers of particular animals used could change. For example, more mice might be used, because transgenic mice produced by the microinjection of DNA into fertilized mouse eggs constitute a powerful system for the study of specific genes (Bieberich and Scangos, 1986).


No comprehensive data on the use of animals for research, testing, and education in the private sector are available, and trends in this use are difficult to gauge. Federal in-house use amounts to about 1.6 million animals, or less than 10 percent of the estimated 17 million to 22 million animals used annually for research, education, and testing in the United States. A uniform system of reporting, while costly, would help to determine more accurately the numbers of animals used in research, which would make it possible to assess the impact of policy on trends in animal use. Animals are used extensively in testing the safety and efficacy of compounds produced by the chemical, cosmetic, and drug industries. Commonly used tests include those for acute toxicity, eye and skin irritation, repeated-dose chronic toxicity, carcinogenicity, developmental and reproductive toxicity, neurotoxicity, mutagenicity, and biological screening. Future technologies might afford ways of reducing animal use, or they might lead to a need for more animals or to shifts in the relative numbers of different species used.

Copyright © National Academy of Sciences.
Bookshelf ID: NBK218261


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