Expert Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

Many scientific advancements in biomedical research would not be possible without the use of laboratory animals. Proper care of animals used in research has been an ongoing priority for the scientific community, and there are many laws and regulations that govern the use of animals in research. It has become more widely recognized that animals may experience distress in a laboratory setting, and that this distress may interfere with the animal's overall welfare, disrupt scientific experiments, and result in unforeseen behavioral and physical changes. Recent scientific progress in the fields of stress and distress, along with greater sensitivity by scientific investigators and the public, have warranted the development of an updated set of guidelines for the recognition and alleviation of distress in laboratory animals. This report updates 1992 National Research Council guidelines for decisions regarding the care and use of animals in the research environment. The report concludes that more research in the area of distress is necessary in order for scientists to make objective, informed decisions concerning the improvement of laboratory animal welfare.

Key Messages

  • Because most laboratory animals live outside normal habitats, they should, to the extent possible in an artificial environment, have the opportunity to express species-specific behaviors. Animal welfare evaluations should consider conditions of housing, husbandry, enrichment, and socialization.
  • Efforts to avoid or minimize distress should follow the principles of the Three Rs: refine, reduce, and replace, which apply to daily husbandry as well as experimental procedures.
  • To address situations of unanticipated distress, the investigator, veterinary staff, and animal care personnel, working as a team and in compliance with the current regulations, should establish a plan to alleviate the distress.
  • Until more research is available, validated practices seeking what is best for the animals while maintaining the integrity of research protocols (i.e., the use of performance standards) should be used.
  • Even if a universally accepted definition existed, it could not be applied across all species and all conditions, because of the differential impact of the strain, age, gender, genetic background, and environment.
  • Investigators who engage in research on distress using laboratory animal models, should, in consultation with the veterinarian and the IACUC, develop a plan that establishes limits to the levels of distress allowed in the experimental protocol.
  • Scientific research does not yet support objective criteria or principles with which to qualify distress objective scientific assessment of subjective emotional states cannot be made, and while there is often a measure of agreement on the interpretation of physiologic and/or behavioral variables as indicators of stress, distress, or welfare status, there is not always a direct link.