University Research Compliance Office

Guideline #1

Signs for Assessing Morbid and Moribund Rodents

1. References: The Guide for the Care and use of Laboratory Animals: Eighth Edition. Nation Research Council. Chapter 2, pp.27-28 and Chapter 4, pg.114.

2. Purpose/Scope: These guidelines are intended for assessing morbidity, and impending mortality in rodents so as to prevent death as an endpoint, minimizing pain and distress. Inexperienced personnel may not easily recognize signs associated with severe illness or distress in rodents. Consequently, knowing these sometimes subtle clinical manifestations can aid animal care personnel and researchers in providing optimum care. The Animal Monitoring Plan within the approved animal care and use protocol (ACUP) must define parameters, monitoring criteria and interventions that will be implemented during the experiment.

3. Signs for Judging Morbidity (disease/illness) in Rodents

  • Rapid breathing rate
  • Breathing rate very slow, shallow, and labored
  • Rapid weight loss
  • Ruffled fur (rough hair coat)
  • Hunched posture
  • Hypothermia or hyperthermia (changes in body temperature that can often be detected by just touching the animal)
  • Ulcerative dermatitis or infected tumors
  • Inappetence (lack of appetite)
  • Diarrhea or constipation


4. Signs for Judging the Moribund Condition (state of dying) in Rodents

  • Signs for morbidity plus:
    • Impaired ambulation (often resulting in the inability to reach food or water easily)
    • Evidence of muscle atrophy or other signs of emaciation (body weight is not always proportionate)
    • Any obvious prolonged illness including such signs as lethargy (drowsiness, aversion to activity, lack of physical or mental alertness), prolonged inappetence, bleeding, difficulty breathing, central nervous system disturbances, or chronic diarrhea or constipation
    • Inability to remain upright
  • Federal guidelines authorize veterinary staff to euthanize animals in states of unauthorized, uncontrolled pain or distress. The PI is strongly encouraged to work closely with CMG veterinary staff in cases where this situation may exist.

LAST REVIEWED AND ADOPTED BY THE IACUC: July 21, 2022