Establishing Humane endpoints


To establish humane endpoints for use during experimental procedures. 

Experimental studies may involve procedures that cause mortality or clinical symptoms of morbidity in animals. The Principal Investigator and the IACUC must consider the selection of the most appropriate endpoint(s). 

Federal Guidelines require that endpoints are determined for animals use in research and require the consideration of (4) areas:

  1. Anticipated adverse effects the research animals may experience (e.g. pain, distress, illness). 
  2. Most Likely time course and progression of these adverse effects. 
  3. Earliest most predictive indicators of present or impending adverse effects. 
  4. Justification of the humane endpoint to meet the scientific requirements of the study. 

Optimally, studies are terminated when animals begin to exhibit clinical signs of disease if this endpoint is compatible with meeting the research objectives. Such endpoints are preferable to death or a moribund state as endpoints since they minimize pain and distress. 


Guide for the Care and Use of Laboratory Animals, 8th edition, page 27


Humane Endpoint Criteria: An animal in chronic pain or distress that cannot be relieved by analgesics, must be euthanized unless prior scientific justification for these humane endpoints are approved by the IACUC. The presence of one or more of these criteria below may be indications for euthanasia. The clinical signs, depending on severity and duration, that may constitute an endpoint include, but are not limited to: 
  • Hunched posture, lethargy or persistent recumbency
  • Rough or unthrifty hair coat
  • Dyspnea
  • Dehydration
  • Anorexia/Rapid weight loss
  • Circling or head tilt 
  • Limb paralysis 
  • Chronic Diarrhea 
  • Jaundice and/or anemia
  • Bleeding from any orifice
  • Self-induced trauma
  • Any condition interfering with eating or drinking 
  • Excessive or prolonged hyperthermia or hypothermia

If experiments will result in predictable debilitation, the PI must describe the expected time frame for this to occur, and provide a plan in the approved protocol, which documents that:
  1. The minimum number of animals necessary to achieve statistical significance will be used;
  2. Animals reaching the terminal phase of the study will be monitored at least twice daily (in the early morning and late afternoon including weekends and holidays);
  3. Any animals evidencing clinically abnormal behavior will be removed from group housing situations and housed individually with easy access to food and water; and
  4. Written records of all monitoring sessions, indicating the time of the observations, the person observing the animals, and any observations such as the number of animals evidencing clinically abnormal behavior and the number of animals found dead, must be maintained and made available to the IACUC and outside regulatory personnel upon request.

Death as an Endpoint
While it is preferable to use the earliest endpoints compatible with the scientific requirements of each study, there are studies that require moribundity or mortality as an endpoint. The moribund condition is defined as a clinically irreversible condition leading inevitably to death. In these studies, animals are permitted to die or become moribund, as a result of experimental procedures. This is allowed only in rodents and must be approved by the IACUC.
Policy Adoption Date: 03/12/2013
Reference Minutes: 03/12/2013