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The Physicians Committee

NEWS RELEASE June 27, 2006

New Scientific Review Raises Scientific and Ethical Questions about the Use of Rodents in Experiments

Paper in July’s Laboratory Animals Finds Rodents’ Behavioral Needs Thwarted in Laboratories

WASHINGTON–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 in the July issue of the journal

Laboratory Animals.

In “Laboratory Environments and Rodents’ Behavioral Needs: A Review,” author Jonathan Balcombe, Ph.D., an ethologist with the Physicians Committee for Responsible Medicine, 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.

Dr. Balcombe’s findings also show that physiological and psychological effects of laboratory housing contaminate scientific data, amplifying the futility of using rodents to advance human health. Unfortunately, the U.S. 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,” says 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.”

In 2004, Contemporary Topics in Laboratory Animal Science published a review of the scientific literature by Dr. Balcombe showing that mice, rats, and other animals show marked physiological stress responses to routine laboratory procedures. Dr. Balcombe is also the author of Pleasurable Kingdom: Animals and the Nature of Feeling Good, a new book from Macmillan that explores the scientific and ethical implications of animals’ ability to feel pleasure.

Founded in 1985, the Physicians Committee for Responsible Medicine is a nonprofit health organization that promotes preventive medicine, conducts clinical research, and encourages higher standards for ethics and effectiveness in research.

Media Contact:
Patrick Sullivan


Jonathan Balcombe, Ph.D.
Jonathan Balcombe, Ph.D.
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