Lab Mouse Enrichment and Research Welfare

Laboratory mice are the most numerous research animals. Enrichment provision improves their welfare and enhances research quality by reducing stress-related variability.

Key Facts

An estimated 80 million mice are used in research globally each year
Standard laboratory caging has historically been barren — no nesting material, hiding places, or complexity
Nesting material is a high-priority enrichment for mice: they build nests for thermoregulation and security
Enriched mice show less anxiety-related behavior, which can reduce confounding in behavioral studies
The 3Rs framework mandates Refinement of procedures to minimize suffering in all animal research

Welfare Considerations

Laboratory mouse enrichment is an area where welfare improvement and research quality improvement align directly. Stressed, under-enriched mice show higher baseline cortisol, altered immune function, and increased behavioral variability — all of which confound research results. Providing nesting material, hiding tubes, and social housing reduces stress markers and improves reproducibility. The scientific argument for enrichment reinforces the ethical argument, yet implementation is still inconsistent across institutions.

What You Can Do

Advocate for mandatory enrichment provision for laboratory mice in research regulations
Support institutional animal care and use committees that require enrichment justification for any deprivation
Share the scientific literature on enrichment and research quality with researchers who question enrichment
Support organizations auditing and publishing laboratory animal welfare standards
Fund research into enrichment that does not confound specific experimental designs