Menke, C., Pisharath, H., Goodchild, L. et al. 2018. The use of enrichment to reduce fighting in male laboratory mice. Laboratory Animal Science Professional 6(1) (March), 44-45.

Typical husbandry solutions for aggressive mice are individual housing or separation into smaller groups. Individual housing is stressful to mice, while separation into smaller groups can increase housing-related costs for the researchers. To alleviate these issues, we looked into providing enrichment items that function as visual obstructions to encourage continued group housing in a colony of exclusively male mice. Our results showed that the 2-week period with standard enrichment resulted in 15 instances of fighting requiring separation of animals. Only 3 cages of mice fighting were observed when the enrichment was increased. By increasing the enrichment in the cages, group housing was maintained in 90% of the cages significantly reducing time and associated supplies required to maintain this colony of male mice. Though 4 different types of enrichment devices were used to reduce aggression in this study, we believe that extra Crink-l’Nest paper provided adequate visual obstruction for group-housed male mice to remain compatible. It is possible for mice to form stable group overtime but we have not seen a decrease in fighting overtime in this colony until this study.