Mice and Rats in Research
No field of research that we know of excludes mice and rats from experimentation. Cancer research, genetics, immunology, virology, the behavioral sciences, aging, HIV/AIDs, Alzheimer’s, alcoholism, diabetes, obesity, radiation effects, drug addiction, new drug testing and more are studied in mice and rats in the questionable hope that what applies to rodents will apply to humans.
Laboratory mice and rats are estimated to account for up to 95% of animals used in laboratory research but are specifically excluded from coverage by the Animal Welfare Act. Researchers feared that including mice and rats in the Animal Welfare Act would exhaust USDA funds and compromise the AWA’s enforcement of protection of other animal species. Because researchers are not required to report the number of these species used in research protocols, the exact number of these species used annually in research labs in the U.S. is unknown.
Over the past decade, researchers have relied heavily on mice and rats in genetic studies designed to add or “knock out” genes in these organisms to study gene function. The National Institutes of Health has even supported an initiative called the “Knock Out Mouse Project,” an endeavor to create 8500 different mouse strains, each with a different mouse gene “knocked out.” The “Knock Out Rat Consortium” has a similar goal, to create single gene disruptions in every gene of the rat genome. Projects such as these, as well as the development of mice and rats engineered to express human genes, have tremendously increased the number of these animals available for research, and unfortunately, will continue to do so.
There are several issues with reliance on mice and rats in such experiments. Often, despite adding or knocking out genes in these animals, researchers have difficulty assessing the outcome of these experiments -- they are unsure of what “phenotypic” effect to look for in these modified mice and rats, that is, what changes in observable traits occurred as a result of the gene add in or knock out. Perhaps more importantly, what occurs in mice and rats does not translate directly to what happens in humans, especially since researchers report differences between different strains of mice during experiments. And it has been documented that laboratory mice and rats develop distinct metabolic profiles that can skew drug toxicity and metabolism studies.