assessing, or alleviating distress. Because minimization or elimination of distress experienced by laboratory animals is not only a regulatory requirement but also a moral obligation, it is imperative to attempt an evaluation of the state of the science and to translate current scientific knowledge into practical guidelines for use in laboratory animal facilities. Specifically, the Committee was tasked with preparing

a report on stress and distress [that] will review the current scientific literature regarding mechanisms of stress and distress for animal models used in biomedical research as well as the literature regarding methods for recognizing and alleviating distress. Emphasis will be placed on: the scientific understanding of causes and functions of stress and distress; determining when stress becomes distress; and identifying principles for recognition and alleviation of distress. Specific emphasis will be placed on the identification of humane endpoints in situations of distress and principles for minimizing distress in laboratory animals. While all possible scenarios cannot be included in this document, general guidelines and examples will be given to aid Institutional Animal Care and Use Committee (IACUC) members, investigators and animal care staff in making decisions about protocols using laboratory animals under current federal regulations and policies. Recommendations will be based on the most current scientific data where such data are available. The Committee will also identify gaps in the scientific literature where additional research data are needed.

The Committee approached its task from the perspective of performance standards without describing—among others—factors such as intensity, duration, or types of perturbations, in part because this is an advisory document about an insufficiently understood phenomenon, but also because the Committee members believe that—within the current state of science—the best approach to recognize and alleviate distress is through best practices and professional judgment.


Various views, definitions, and language have been used in the discussion of stress and distress. Current scientific knowledge supports the concept that stress is a real or perceived perturbation to an organism’s physiological homeostasis or psychological well-being. In its stress response, the body uses behavioral or physiological mechanisms to counter the perturbation. Events that precipitate stress (called stressors) can elicit any of a number of coping mechanisms or adaptive changes, including behavioral reactions, activation of the sympathetic nervous system and adrenal medulla, secretion of stress hormones (e.g., glucocorticoids and prolactin), and mobilization of the immune system.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement