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Mice and Rats in Research

To the best of our knowledge, every field of research includes the use of mice and rats in experimentation. There are mice and rats used in research for cancer, genetics, immunology, virology, the behavioral sciences, aging, HIV/AIDS, Alzheimer’s, alcoholism, diabetes, obesity, radiation effects, drug addiction, new drug testing and more. These areas use mice and rats in the questionable hope that what applies to rodents will apply to humans. Perhaps Johns Hopkins toxicologist Dr. Thomas Hartung stated it most succinctly when he said of mice and rats used in research, “We are not 70 kg rats.”  Nature did not intend for these animals to be stand-ins for people, and it is not safe to assume that what occurs in rodents will predict what happens in people.

Over the past decade, the number of genetically modified animals has soared globally, with mice and rats used in research for experiments in which genes are added to the animals or “knocked out” in efforts to study gene function. The National Institutes of Health is supporting an initiative called the “Knock Out Mouse Project,” an endeavor to create 8,500 different mouse strains, each with a different mouse gene knocked out. The “Knock Out Rat Consortium” has a similar goal, to knock out genes in rats to create models that can be used for functional genomics studies and for drug discovery. Projects such as these have tremendously increased the number of mice and rats used in research and, unfortunately, will continue to do so. 

Despite the prevalence of mice and rats used in research by the scientific community, the Animal Welfare Act (AWA), the primary federal law that regulates the use of animals in research, specifically excludes these and other animals, including birds and invertebrates, from the definition of “animal.” Researchers argued that including these animals in the AWA would be a costly administrative burden and exhaust United States Department of Agriculture (USDA) funds and compromise the AWA’s enforcement of protection of other animal species. The result of this omission is that researchers are not required to report the number of these species or how they are used in research protocols to the USDA. As a result, no one knows the exact number of mice and rats used in research in the U.S. every year.

In an effort to get more clarity on the use of these and other animals in scientific experimentation, a study published in February 2015 in the Journal of Medical Ethics used data from Animal Welfare Assurance documents to get a sense of animal use by the 25 largest public and private recipients of National Institutes of Health funds—including information on animals not covered under the Animal Welfare Act. These Assurances are filed, at least once every four years, by institutions that obtain Public Health Service funding. The documents, acquired by Freedom of Information Act requests, include information on the inventory of animal species used at the research facilities—including mice and rats.

Results of this study revealed that over a 15-year period, from 1997 to 2012, the use of animals among the largest federal grant recipients increased nearly 73%, driven largely by increased use of mice. This study shed much needed light into the use of non-AWA covered animals in the U.S., as the USDA Animal and Plant Health Inspection Service (APHIS) fails to provide this basic information to the general public.

Interestingly, what message would the general public get regarding animal use by visiting the APHIS website?  During the same time frame examined in the study, 1997-2012, APHIS reports indicate there was a 25% decrease in animal use. While this is not an apples-to-apples comparison, as APHIS annual reports are compiled from many more research institutions and include only AWA-covered animals, the government reports on animal use that are published and publicly available on the USDA website offer a very different and misleading picture regarding animal use in the United States.