Once humane endpoints are established, they should be defined carefully and thoroughly in the animal-use protocol that is submitted to the IACUC for review. The protocol should also establish an adequate but practical frequency of observations and describe the documentation that will be included in an animal’s health record. The frequency of observations depends on the nature of the experimental manipulation or disease state and the expected rate of change in an animal’s condition.

In some cases, such as genetically modified animals, unpredicted or unintended alterations may occur that adversely affect animal well-being (Stokes, 2000). When developing new types of genetically modified animals, a PI should predict alterations and outcomes based on what is known about the gene of interest, so as to develop humane endpoints (Dennis, 2000). In addition, phenotype screens and measures of general health and well-being may be appropriate to detect unpredicted, adverse alterations in an animal’s physiology. If unexpected outcomes do occur, a change in the frequency of observation or an adjustment of the humane endpoint(s) may be warranted.

Another issue is to identify the individuals who will be empowered to decide that a humane endpoint has been reached and that the animal should be removed from the study and/or euthanized. These individuals should be well trained to recognize what is normal and abnormal for the species, and they should clearly understand what is considered an acceptable or unacceptable condition as specified in the animal-use protocol. A clear designation of authority and responsibility to decide on and carry out euthanasia is essential. Ideally, more than one person should have this authority to accommodate for absences. The IACUC should ensure that a designated contact person is listed in the protocol and that someone will be available for consultation or decisions at all times. The responsible veterinarian must have full authority to carry out humane euthanasia when circumstances warrant, although ideally this should be done after consultation with and with the consensus of the research team.


The Guide (p. 10) states that the method of euthanasia should be considered in the preparation and review of animal-use proposals. The AWRs and the Guide state that the method of euthanasia must be consistent with the current version of the Report of the AVMA Panel on Euthanasia (AVMA, 2001) unless a deviation is justified for scientific or medical reasons. The AWRs stipulate that guidance on appropriate euthanasia techniques be provided to investigators and animal-care staff by the veterinarian (AWR 2.33 (b)(4)). The AWRs also require that records be maintained on dogs and cats that are euthanized (AWR 2.35 (c)(2)). The IACUC must review and approve the method of euthanasia and must determine whether the proposed endpoint of the study is appropriate, inasmuch as the AWRs further require that “animals that are in severe or chronic pain or distress that

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