Intermale aggression among cage mates is a natural behavior in mice, serving to establish social hierarchies. However, this behavior can escalate, leading to injuries ranging from minor wounds to severe trauma that requires euthanasia. Traditional mitigation strategies—such as removing the aggressor or single-housing—may reduce harm but can negatively impact welfare as they can increase stress and social isolation. A study in Laboratory Animals explored whether environmental enrichment could reduce aggression in group-housed CD-1 male mice. The team tested various enrichment combinations and found that the presence of nesting material alongside tunnels and/or a running wheel/igloo significantly reduced aggression compared to housing without nesting material. These results suggest that specific forms of enrichment can redirect aggressive tendencies toward alternative behaviors like nesting or exploration. This approach offers a welfare-friendly strategy for managing aggression in laboratory mice without the drawbacks of social deprivation.
Original reference: Veness, A. et al. Lab. Anim. https://doi.org/10.1177/00236772251333986 (2025)
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