Social housing supports the behavioral needs and wellbeing of laboratory mice, with females being particularly sensitive to the presence of cagemates. Few studies, however, have examined how changes in cage density over time affect survival in a sex-specific manner. In a new study, researchers analyzed data from 2,635 UM-HET3 mice in the National Institute on Aging’s Interventions Testing Program (ITP) across three sites (The Jackson Laboratory, the University of Michigan and the University of Texas) to assess whether housing density influences longevity. Mice in the ITP were housed in same-sex cages (median = 3 per cage), and they were not rehoused to new cages when their original cagemates died. Using Cox frailty models, the researchers show that female mice exhibited a significant increase in the risk of death as cage density declined over time, while male survival was unaffected. Although these findings require validation in other strains, they highlight important considerations for longevity studies in mice and suggest that interventions such as replacing cagemates after death should be evaluated.
Original reference: Mokalla, T, R. et al. Geroscience https://doi.org/10.1007/s11357-025-02080-z (2026)
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