Environmental Enrichment for Laboratory Mice

Laboratory mice are among the most widely used research animals. Providing appropriate enrichment dramatically improves their welfare without compromising research validity.

Key Facts

Approximately 100 million mice are used in research worldwide each year
Standard laboratory housing deprives mice of the ability to burrow, nest build, forage, or exercise freely
Nesting material is among the most important enrichments for mice, enabling thermoregulation and a sense of security
Running wheels are highly motivated enrichments for mice — they run voluntarily for hours daily
Enriched housing generally does not increase behavioral variability in ways that compromise research quality

Welfare Considerations

Laboratory mouse welfare is an area where significant improvement is achievable at low cost. The anxiety and boredom experienced by mice in barren standard caging impairs welfare and paradoxically reduces research reproducibility by increasing stress-related physiological variability. Nest-building materials, running wheels, tubes for shelter, and foraging enrichments address fundamental mouse behavioral needs at minimal cost. The Three Rs framework — Replace, Reduce, Refine — mandates refinement of laboratory animal housing, yet implementation of even basic enrichment remains inconsistent across institutions. Advocacy for mandatory enrichment standards backed by regulatory enforcement would improve welfare for hundreds of millions of animals.

What You Can Do

Support institutions and funding bodies that mandate enriched housing for laboratory mice
Advocate for regulatory enforcement of the Three Rs including the Refinement of housing standards
Support NC3Rs and similar organizations developing and promoting laboratory animal welfare improvements
Ask universities and research institutions about their animal care and enrichment standards
Support the development of non-animal research methods that can replace mouse models where validated