The 8th edition of the Guide for the Care and Use of Laboratory Animals (the Guide, page 51) specifies that social housing is the expectation for social species [1]: “Social animals should be housed in stable pairs or groups of compatible individuals unless they must be housed alone for experimental reasons or because of social incompatibility.” According to the Guide, single housing of social species should be the exception and justified based on experimental requirements or veterinary-related concerns about animal well-being. The Guide also requires that single housing be limited to the minimum period necessary and that enrichment be offered, such as positive interaction with the animal care staff and additional enrichment items. See also the ARC Policy on Environmental Enrichment.

Further, an AAALAC Position Statement notes that “Social housing will be considered by AAALAC International as the default method of housing unless otherwise justified based on social incompatibility resulting from inappropriate behavior, veterinary concerns regarding animal well-being, or scientific necessity approved by the IACUC (or comparable oversight body).”

Based on the above, the ARC requires that all animals housed at UCLA be socially housed unless single-housing is either scientifically justified and documented in the approved ARC protocol or required due to one of the following:

  • Separation of animals by the veterinary staff for reasons such as aggression/fighting, clinical treatment (e.g., administration of medication), or post-operative recovery.
  • Attrition that results in a single animal that cannot be re-paired with other animals.
  • Breeding colony management-related issues, such as females that are separated for copulatory plug checks, males that are resting between matings, and separation of pregnant mice in harem breeding settings to avoid cage overcrowding.

All other reasons for single-housing must be research-specific and documented in an approved ARC protocol.

Researchers that singly house animals for any of the reasons listed above must make a notation on the cage card to indicate the reason for the arrangement using one of the five categories highlighted in red above (i.e., aggression, attrition, breeding, treatment, protocol exception). In some cases (e.g., PI-restricted rodent areas in DLAM) and for certain species (e.g., USDA-regulated species where single housing arrangements may be determined by or in concert with DLAM), DLAM may assist the PI in documenting the reason for single housing on the cage card or via other methods according to DLAM SOPs.

[1] Social animals include mice, rats, gerbils, guinea pigs, dogs, pigs, rhesus macaques, bats, frogs, lizards, anoles, salamaders, zebrafinches, pigeons, scrub jays, zebrafish; and may include rabbits and chinchillas.


Approved 1/12/15, Revised 9/24/18