Institutional Social Housing and Environmental Enrichment Policy

IACUC Policy: 055-04, Effective Date: 04/19/2019, Last Revision: 10/21/26

Overview/Purpose

Social housing and environmental enrichment are addressed at the level of the individual housing area due to the size and scope of the program at The Ohio State University. This policy will describe how social housing and environmental enrichment are addressed within the program and will describe programmatic exceptions to social housing.

Definitions

Environmental Enrichment: The provision of structures and resources that facilitate the expression of species-typical behaviors and promote psychological well-being through physical exercise, manipulative activities, and/or cognitive challenges according to species-specific characteristics.
Social Enrichment: Appropriate social interactions among members of the same species (conspecifics) or compatible species.
SOP: Standard Operating Procedure
SMP: Standard Management Plan

Requirements

Environmental enrichment plans for animals owned and housed at The Ohio State University should be included in the associated SOP or SMP for that respective housing facility.
Enrichment will be provided per facility SOP or SMP unless exempted by the IACUC in the approved animal use protocol due to scientific reasons or by an OAV veterinarian for clinical reasons.
Social species must be housed in stable pairs or groups unless:
- Scientific justification is provided in an IACUC approved Animal Use Protocol.
- An OAV veterinarian exempts an animal for health or behavioral reasons (requires documentation).
- The animal is recovering from surgery (up to 72 hours).
- A female animal is visibly pregnant.
- The animal is a retired breeder.
- A single animal remains from a cohort due to attrition of cage or pen mates, separation due to aggression, being the last remaining experimental member, being ordered as a single animal, or having no compatible cohort available at the time of weaning.
Note: Regrouping of singly housed adult male mice frequently leads to an increased incidence of fighting and is therefore discouraged for most strains.
Adult boars, stallions, bulls, rams and bucks are not considered social animals and may be housed singly.
Additional enrichment must be provided for singly housed animals except when:
- Exempted for scientific (outlined in protocol) or veterinary reasons.
- Withheld for animals housed in metabolic caging due to the potential for interference with data collection.
Cages of socially compatible rats may exceed the Guide recommendations for floor space based on cumulative body weight. In such cases, animals will remain pair-housed to maintain social housing unless performance indices necessitate separation.

Revision History

055-00 – new policy approved 04/19/2019
055-01 – reviewed and approved 04/15/2022
055-02 – reviewed and added programmatic exception to metabolic caging, approved 01/17/2025
055-03 – clarified withholding enrichment for metabolic caging used and approved in protocols. Also added a note for regrouping male adult mice; Approved 04/18/2025
055-04: Added qualifiers to allow single housing of retired breeders, added additional intact male species to single-housed list, added provisions to maintain social housing for pair-bonded rats with cumulative body weight exceeding Guide-recommended floor space; approved 10/21/2026

Article ID: 45
Created: May 20, 2024
Last Updated: November 6, 2026

Online URL: https://ohiostateresearch.knowledgebase.co/article/institutional-social-housing-and-environmental-enrichment-policy-45.html