Unrelieved pain and distress in animals: an analysis of USDA data on experimental procedures.

Pain and distress are core issues in the field of animal experimentation and in the controversy that surrounds it. We sought to add to the empirical base of the literature on pain and distress by examining government data on experimental procedures that caused unrelieved pain and distress (UPAD) in animals. Of the species regulated by the U.S. Department of Agriculture (USDA), most of the approximately 100,000 animals subjected to UPAD during the year analyzed (1992) were guinea pigs and hamsters. Most of these animals were used in industry laboratories for various testing procedures, primarily vaccine potency testing. We discuss the limitations of the USDA data and recommend changes to the current reporting system. By identifying experimental procedures that cause UPAD in large numbers of USDA-regulated animals, the present analysis can be viewed as a means of identifying priorities for research and development of alternatives methods (replacements, reductions, and refinements).