Acclimation for Newly Received Laboratory Animals
Number: IACUC-POL-038
Responsible Office: Office of Research and Creative Scholarship (ORCS)
Applies to: Principal Investigators Conducting Animal Research or All animal research and teaching protocols involving live vertebrate animals
1. Purpose
Transportation unavoidably causes stress in animals. Although stress is not always an adverse experience and is a necessary and regular aspect of life, it results in physiological changes during transportation and for some period thereafter. Utilizing animals before their physiological status has normalized can have unintended and confounding effects on research outcomes. Stress associated with transportation has been shown to affect multiple physiological systems, including cardiovascular, endocrine, immune, central nervous, and reproductive systems.
The Guide for the Care and Use of Laboratory Animals and the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching recommend a period of stabilization and acclimation for newly received animals prior to their use in research or teaching. The purpose of this policy is to provide standard, minimum recommendations to Principal Investigators (PIs) regarding appropriate acclimation periods for animals following transport.
2. Background
Stress associated with transportation can have widespread effects on physiological systems in laboratory animals, including changes in the cardiovascular, endocrine, immune, central nervous, and reproductive systems. While these changes are often short-lived, they may confound research outcomes if animals are utilized before homeostasis is restored and physiological measures return to baseline.
Elevations from baseline physiological parameters generally normalize within 1–7 days following transport. However, animals that are young, severely stressed, and/or possess stress-sensitive genotypes may exhibit altered physiological measures for several weeks. Accordingly, an appropriate acclimation period following transportation is recommended.
The Guide for the Care and Use of Laboratory Animals states:
“Newly received animals should be given a period for physiologic, behavioral, and nutritional acclimation before their use. The length of time for acclimation will depend on the type and duration of animal transportation, the species, and the intended use of the animals. For animals not typically housed in research settings, consideration should be given to providing means to assist with their acclimation. The need for an acclimation period has been demonstrated in mice, rats, guinea pigs, nonhuman primates, and goats, and time for acclimation is likely important for other species as well. Animals newly received into the animal facilities should be given a period of acclimation to ensure physiologic, psychological, and nutritional stabilization before their use.”
3. Policy Statement
All newly received laboratory animals must be allowed an appropriate acclimation period prior to use in research or teaching activities, unless otherwise justified and approved by the IACUC or Attending Veterinarian. Minimum acclimation periods are outlined below; longer periods may be required based on veterinary determination or specific research needs.
4. Acclimation Periods
Rodents and Non-Mammalian Vertebrates
All rodents and non-mammalian vertebrates must have a minimum acclimation period of 72 hours (3 days) following arrival and prior to use for experimental or breeding purposes, unless otherwise scientifically justified and approved in an IACUC-approved Animal Use Protocol (AUP).
USDA-Covered Species and Larger Mammals
All USDA-covered species must have a minimum acclimation period of 7 days following arrival before being used for experimental purposes, unless otherwise scientifically justified and approved in an IACUC-approved Animal Use Protocol.
5. Exceptions
- The IACUC may grant exceptions to the acclimation period when scientifically justified and clearly described in the approved protocol.
- The Attending Veterinarian or designee may shorten or waive the acclimation period on a case-by-case basis.
- Transport of animals involved in clinical cases requiring veterinary treatment may occur at the discretion of the veterinarian.
6. References
- Guide for the Care and Use of Laboratory Animals, 8th Edition, p. 111 (Obernier and Baldwin 2006; Capitanio et al. 2006; Conour et al. 2006; Kagira et al. 2007; Landi et al. 1982; Prasad et al. 1978; Sanhouri et al. 1989; Tuli et al. 1995).
- Conour LA, Murray KA, Brown MJ. Preparation of animals for research—issues to consider for rodents and rabbits. ILAR Journal. 2006;47(4):283–293.
- Grandin T. Assessment of stress during handling and transport. Journal of Animal Science. 1997;75:249–257.
- Obernier JA, Baldwin RL. Establishing an appropriate period of acclimatization following transportation of laboratory animals. ILAR Journal. 2006;47(4):364–369.
- Tuli JS, Smith JA, Morton DB. Stress measurements in mice after transportation. Laboratory Animals. 1995;29(2):132–138.
- USDA Animal Care. Animal Welfare Act and Animal Welfare Regulations. 2019; pp. 111–121.
- PHS Policy on Humane Care and Use of Laboratory Animals.
- NRC. Preparation of Animals for Research. ILAR Journal. 2006;47(4):281–375.
7. Review, Approval and Version History
|
Version |
Date |
Description of Changes |
Approved By |
|---|---|---|---|
|
1.0 |
February 10, 2026 |
Initial policy creation |
IACUC |