Scientific evidence strongly supports group housing for laboratory mice. Implementing social housing improves welfare and may actually improve research reproducibility.
Group housing welfare for laboratory mice involves recognizing that individually housed mice experience chronic social deprivation that affects their entire physiological state. The elevated baseline cortisol of singly housed mice is not merely an inconvenience - it represents ongoing stress with immune, behavioral, and metabolic consequences. These physiological changes may also affect experimental outcomes, creating a scientific argument for social housing that complements the welfare argument. Research institutions that continue to use single housing without specific scientific justification are accepting both a welfare harm and a potential confound in their research - a dual cost that the evidence does not support.