Can Medical Research on Animals be Justified?

The use of animals in medical research is morally unjustifiable not just because it hampers medical progress for humans, but because it is inhumane. Animal testing inherently and unavoidably causes animal pain, distress, and suffering. In many cases the suffering may be especially severe and prolonged, such as in tests for acute and chronic toxicity, carcinogenicity, and skin irritancy and corrosivity.

Although the U.S. Department of Agriculture is supposed to document how many animals experience pain and distress without relief from drugs, reports from other countries and research conducted by the Humane Society of the United States suggest that the agency vastly under-reports these incidences. What’s more, government oversight of animal research completely excludes mice, birds, rats, and fish, who account for the great majority of animals used in testing.

Notwithstanding the problems of under-reporting of pain and distress, deaths associated with animal housing, transport, and usage, and the nature of many experiments themselves, stress and distress arising from everyday laboratory living conditions create an even greater incentive for replacing the use of animals in laboratories.

A recent literature review reported on the effects of common laboratory routines, including handling, blood collection, and cleaning cages, on physiological markers of stress. The authors related that animals exhibited rapid, pronounced, and statistically significant elevations of physiological stress indicators such as heart rate and blood pressure. The data suggest that significant fear, stress, and possibly distress are predictable consequences of standard laboratory procedures, and that these phenomena not only cause animal suffering, but also distort physiological measures and scientific outcomes.

The animals’ stress is compounded by standard laboratory housing conditions, which typically deprive the occupants of opportunities to engage in essential natural behaviors.

Manifestations of distress include self-mutilation, compulsive hair pulling, bar gnawing, head banging, pacing, rocking, and other signs of neurosis. One chimpanzee in a U.S. laboratory, who underwent 289 procedures, including 40 liver biopsies, over 14 years, had chewed off his thumbs and index finger out of anxiety. Even after he was released to a sanctuary, he was often found choking, gagging, and convulsing.