The University of Iowa

Social Housing of Species (Policy)

Housing of Social Species (Policy)


The IACUC has provided a set of guidance documents (Policies, Guidelines, and Informational Sheets) for use when planning animal procedures at the University of Iowa. An exception to a Policy must be described and justified in the Animal Protocol and approved by the full IACUC at a convened monthly meeting.


The Guide to the Care and Use of Laboratory Animals states that members of a social species should be socially housed whenever possible. The purpose of this policy is to define what constitutes an acceptable justification for single housing of social species. It is the policy of the IACUC that social experience is the standard for social species. However, the IACUC recognizes that not all members of social species are compatible and that there are circumstances when social housing is not possible.


Potential social species at the University of Iowa:  dogs, ferrets, pigs, sheep, goats, rabbits, most rodents (excluding: male mice, female hamsters), chickens, turkeys and pigeons.


The following are acceptable justifications for single housing of social species:

  • Justification in Animal Protocol required:

    • Scientific necessity
      • Justification for single housing should be defined for the shortest period of time necessary
  • Justification in Animal Protocol NOT required:

    • Veterinary concerns regarding the well-being of the animal
    • Observed social incompatibility (e.g. fighting, food guarding, etc.)
    • Immediate post –operative recovery
    • Attrition of cage mates
      •  Remaining animals may be combined, if appropriate (DO NOT COMBINE MALE MICE PAST WEANING AGE)
    • Only one animal of a sex or genotype is produced in a litter and no other appropriate weanlings are available for group housing

General Considerations:

  • When social animals must be housed singly:

    • Environmental and/or food enrichment, exercise/release into a larger enclosure, and/or human interaction will be provided, unless scientifically contraindicated
    • Con-specifics will be housed in visual, auditory, olfactory and/or tactile range, whenever possible
  • If primary cage size is the limiting factor for the ability to group house, OAR shall develop a plan to address the need for larger caging

  • Animals that have been singly housed may need gradual introduction to cage mates

    • Veterinary consultation should be used to determine if compatible cage mates can be found


Species Specific Considerations:

  • DOGS:

    • Unfamiliar dogs that will be housed for less than 2 weeks need not be pair housed due to the potential for aggression.
      • Single housed dogs will receive enrichment according to the canine enrichment program

    • Pregnant Jills may be singly housed for up to 14 days prior to whelping.

    •  Males may be group housed at weaning and stay together until they are separated for breeding or research purposes. Group housing males at ages up to pre-puberty, or regrouping previously separated males up to this age may be attempted with veterianry consultation.
      • Attempts to group house sexually mature male ferrets should be done under veterinary supervision

    • Younger than 4 months of age (sexually immature): Should be group housed by sex  if they will be housed in the vivarium for longer than 3 months
    • Older than 4 months of age (sexually mature): Unless previously socially housed and shown to be compatible, should be singly housed
      • Attempts to group house sexually mature rabbits should be done under veterinary supervision
  • MICE:

    •  Male mice are often aggressive and are not considered social
      • Male mice may be housed together only when co-housing occurs at weaning age or earlier
      • Once a male mouse is removed from a male group housing cage (for breeding or prolonged experimental procedures), he may not be returned to a cage with other male mice
  • RATS:

    • Male rats are usually compatible if reared together
      • Unfamiliar adult males should not be combined without due caution and observation

    • Sexually mature female hamsters are aggressive to cage mates and should be housed singly
    • Male hamsters raised together may be compatible
      • Unfamiliar adult males may be aggressive and should not be combined without due caution and observation

Last Reviewed by the IACUC 2/08/2023