The US Department of Agriculture (USDA) reports that in fiscal year 2018, there were 780,070 animals used in research, and another 122,717 held in research facilities but not used for regulated activities. These numbers included dogs, cats, nonhuman primates, guinea pigs, hamsters, rabbits, pigs and sheep. They did not include rats of the genus Rattus, mice of the genus Mus, or birds or fish—despite the fact that these animals make up the overwhelming majority of animals in research.
Studies with animals include basic research such as genetics, developmental biology and behavioral work, as well as applied research such as biomedical research, xenotransplantation (the transplantation of living cells, tissues or organs from one species to another), and toxicology and drug testing. Animals are also used in education (for example, for dissection).
Overall, while research with a few species such as hamsters and rabbits appears to be trending down, the number of pigs and nonhuman primates is increasing.
The number of rats, mice, and fish in research is believed to be increasing dramatically—in large part due to studies involving genetic modification. Annual estimates regarding the number of rats, mice and birds in research range from 25 million to over 100 million. Millions of fish and thousands of amphibians are also used. As these animals are excluded from protection under the Animal Welfare Act (AWA), there is no accounting to the USDA or any other federal agency of these millions of lives that are sacrificed for research, testing and teaching.
A tremendous number of rodents in research are the product of genetic engineering. Often the goal is to more closely mimic human diseases. There are welfare issues associated with breeding such animals (a large number of surplus animals are generated to achieve a small number with the desired genome), as well as issues encountered during the conduct of the research—as these animals have a strong potential for suffering and experience high premature death rates.
Most animals sold for research purposes are bred specifically for this purpose. Commercial breeders are licensed “Class A” by the USDA and required to meet minimum standards under the Animal Welfare Act (AWA). Other animals are wild-caught—among them birds, fish, reptiles, amphibians and some mammals as diverse as nonhuman primates, opossum, and deer mice. USDA-licensed “Class B” dealers also serve as middlemen, acquiring animals from other sources and then selling the animals to laboratories. Some dogs and cats are acquired directly from municipal pounds.
All animals in research should be treated as humanely as possible. Rats, mice and birds, in particular, deserve the legal protection afforded other species via the Animal Welfare Act. Researchers doing work with any animal species should use the “3Rs” as their guiding principles: replacement (substitution with non-animal methods), reduction (methods of obtaining data using fewer animals), and refinement (methods that alleviate or minimize animal suffering and enhance animal welfare).