New Scientific Review Finds Standard Laboratory Housing to Be Inadequate

Standard laboratory housing thwarts the basic behavioral needs of rats, mice, and other rodents, inflicting physiological and psychological harm and raising serious scientific and ethical questions about using these animals in experiments, according to a scientific review by PCRM’s Jonathan Balcombe, Ph.D., in the July issue of the journal Laboratory Animals.

In “Laboratory Environments and Rodents’ Behavioral Needs: A Review,” Dr. Balcombe, who holds a doctorate in ethology from the University of Tennessee in Knoxville, examined more than 200 published studies addressing the ill effects of impoverished housing typical of laboratories. Among the many findings: Both rats and mice value and will work for the opportunity to forage, build nests, explore, and have social contact; rats kept in impoverished environments have smaller brains than stimulated rats; solitary rats try to escape more than group-housed rats; tens of millions of lab-bound mice dig, gnaw, and/or circle neurotically for hours at a time, mostly at night when researchers have gone home; and mice kept in barren cages consume more stress-relieving drugs.

Unfortunately, the Animal Welfare Act does not mandate any “environmental enrichment” for rats and mice in laboratories because rodents are excluded from protection under the act.

“These findings provide further evidence that there is no such thing as a humane animal experiment,” said Dr. Balcombe. “The studies reviewed here show that the welfare of laboratory-caged rodents is compromised when they are confined, isolated, and allowed to develop stereotypical behaviors.”