Research and Sponsored Programs

Social Housing and Enrichment Guideline

Revision Date: April 15, 2026

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The Guide for the Care and Use of Laboratory Animals, the Guide, states that, “Appropriate social interactions among members of the same species (conspecifics) are essential to normal development and well–being”. Social housing of social research animals is the default housing environment at the University of Toledo. Single housing of social species must be justified based on experimental requirements. DLAR veterinary staff may also require individual housing of animals due to medical or behavioral concerns.

The IACUC considers the following as exceptions that do not require prior or ongoing approval from the IACUC:

1. Demonstrated incompatibility within social groups, as determined by the veterinarian. The aggressive nature of individual animals/sex/strains may justify single housing. This incompatibility would be noted if fighting or trauma to cage mates is observed.
2. Breeding, such as pregnant female, female with a litter, or stud male housed individually when designated for breeding (when documented due to strain/species),
3. Veterinary concerns, such as short term (less than 1 week) recovery from surgical manipulation or illness.
4. Only one animal of a sex or genotype is produced in a litter, and no other appropriate weanlings are available for group housing. 
5. Attrition of cage mates
   1. Remaining animals may be combined, if appropriate (see information below on grouping male mice)

Justification for a variance from communal housing for reasons other than those noted above must be submitted for review and approval by the IACUC as part of a new or continuing protocol or via an amendment. Individuals from species that are not socially housed should be provided with additional enrichment. If single housing is required, it should be limited to the minimum period necessary.

Male Mice and Fighting

1. Male mice are often aggressive and are not considered social.
   1. Male mice can be housed together only when they are shipped from a vendor/other institution in compatible groups, co-housed at the time of weaning, or grouped before 4 weeks of age.
   2. Once a male mouse is removed from a group situation (for breeding, due to fighting, or experimental procedures) the animal must not be returned to a cage with other male mice.
2. Consequence of not following this guideline:
   1. Should any previously separated animals, which are not covered by an IACUC approved exemption,e housed back together by the investigator and/or lab members, and be found by the animal care staff, the mice will be separated, and the IACUC will be notified.
   2. The situation will be handled according to the IACUC Standard Operating Procedure for Handling Allegations of Non-Compliance.

Environmental Enrichment

The Guide states: “The primary aim of environmental enrichment is to enhance animals’ well-being… according to species-specific characteristics”. The availability of suitable enrichment devices and practices within the primary enclosure helps achieve this goal. All research animals at The University of Toledo will receive environmental enrichment unless an exception has been approved by the IACUC. Enrichment materials or practices must be designed and applied in accordance with The Guide, in order to enhance the opportunities for the animals to display species specific behavior.