IACUC Policy: Humane Endpoints    
Policy # IBT-204.00 IACUC Approval: February 27, 2014

To assure compliance with the Animal Welfare Act (AWA), the Guide for the Care and Use of Laboratory Animals (the “Guide”), Public Health Service Policy on Humane Care and Use of Laboratory Animals, and institutionally relevant policies, as well as to promote good research. This policy describes the responsibilities and procedures that personnel must follow when determining appropriate, humane endpoints.

This policy applies to all animal care and use subject to oversight by Texas A&M Health Science Center animal facilities and laboratories.

It is the responsibility of the IACUC to:

  • Ensure that protocols define humane endpoints, explore alternatives, and outline procedures to reduce pain and distress
  • Review exceptions to this policy, and scientific justifications for those exceptions as well as death as an endpoint
  • Act on behalf of the institution to investigate and if necessary suspend any activity which violates applicable laws, regulations, standards, guidelines, policies and procedures.

It is the responsibility of the Principal Investigator (PI) or designate to:

  • Adhere to this policy and ensure that all research personnel responsible for monitoring animal pain and distress are appropriately trained and/or experienced.
  • Define humane endpoints
  • Explore alternatives
  • Scientifically justify all endpoints
  • In order to use of death as an endpoint, justification must be provided that no alternative exists
  • Outline procedures that will be taken to minimize pain and distress

It is the responsibility of the AV or designee to provide guidance to the IACUC and investigators on humane endpoints, alternatives, and monitoring pain and distress.

I. General Considerations:

Efforts should be made to minimize pain and distress experienced by animals used in research. To this end, the use of death as an endpoint to experimental studies, rather than performing euthanasia to humanely terminate an animal, is discouraged and should be justified.

Each Animal Use Protocol (AUP), especially those anticipated to result in severe or chronic pain, should describe endpoint(s) and specify a plan and criteria for removal/euthanasia of animals from the study, or the disposition of animals at the termination of the study. For many studies, the endpoint will be euthanasia upon study completion, euthanasia at certain time points, or the return of animals to stock. For studies where moderate to severe clinical signs are anticipated, the endpoint description in the AUP shall include identification of personnel responsible for decision making, specific criteria (body weight, mass size, appetite, etc.) that will be monitored at prescribed frequencies (daily, weekly, etc), and a disposition (treatment, euthanasia, early removal from study, etc.) once those criteria have been met or exceeded.

Animal studies may involve procedures that cause severe clinical signs or morbidity, and investigators should consider the selection of the most appropriate endpoint(s) for their study. This requires careful consideration of the scientific objectives of the study, the expected and possible adverse effects the research animals may experience, the most likely time course and progression of those adverse effects, and the earliest most predictive indicators of present or impending adverse effects. Prior to initiation of the study, the PI should determine criteria that would lead to termination of the study for any animal, when appropriate, and the method of euthanasia to be employed. A clear chain of command for the decision-making process should be documented, including contingency plans if said individuals are unavailable for consultation.

Optimally, studies are terminated when animals begin to exhibit severe clinical signs if this endpoint is compatible with meeting the research objectives. Such endpoints are preferable to death or moribundity (defined by the IACUC as imminent death) as endpoints since they minimize pain and distress.

There must be scientific justification in the AUP for allowing an animal to die without intervention, if goals of the study can be accomplished by euthanizing animals before they become moribund.

Animals involved in experiments that may lead to moribundity or death should be monitored daily (including weekends) by personnel experienced in recognizing signs of morbidity. Once severe clinical signs develop, more frequent observation (2-3 times daily) may be required.

II. Criteria for euthanasia:
The following conditions usually necessitate euthanasia. The PI or designate must provide scientific justification for exemptions:

  1. Rapid weight loss of ≥20% of body weight.
  2. Extended period of weight loss, progressing to emaciated state.
  3. Surgical complications unresponsive to medical intervention.
  4. Combination of the following: poor physical appearance (very rough hair coat, abnormal posture, grunting on exhalation); abnormal behavior (reduced mobility/unconsciousness, unsolicited vocalizations, self-mutilation); severe depression or abnormal/exaggerated responses to external stimuli.
  5. Severe respiratory distress, which is unresponsive to treatment.
  6. Occurrence of a serious injury or trauma from which recovery is unlikely.
  7. Neurological signs (e.g., persistent convulsions, persistent circling, paresis/paralysis) that interfere with eating and drinking and from which recovery is unlikely.
  8. Frank bleeding from any orifice, which is unresponsive to treatment.
  9. One or more skin ulcers that do not heal, depending upon the species and severity of the ulcers.
  10. Criteria for euthanizing animals with tumors are found in the Tumor production policy.


  1. Animal and Plant Health Inspection Service, USDA. US Animal Welfare Act (AWA 1990) and Regulations (PL-89-544, as amended, 7USC Ch. 54) 2008. CFR Title 9, Subchapter A - Animal Welfare. U.S. Government Printing Office, Washington, D.C.
  2. National Research Council. Institute for Laboratory Animal Research. 2011. Guide for the Care and Use of Laboratory Animals. Public Health Service, Bethesda, MD.
  3. Public Health Service Policy on Humane Care and Use of Laboratory Animals http://grants.nih.gov/grants/olaw/references/phspol.htm.
  4. Montgomery CA. 1990. Oncologic and toxicologic research: Alleviation and control of pain and distress in laboratory animals. Canc Bull 42(4):230-237.
  5. Stokes WS. 2002. Humane endpoints for laboratory animals used in regulatory testing. ILAR J 43(Suppl):S31-S38

Version 00 – Initial Approval: February 27, 2014