Lab Mouse Enrichment: Improving Research Animal Welfare

Laboratory mice are the most widely used research animals globally. Simple cage enrichment improves welfare and may also improve scientific validity of research results.

Key Facts

Approximately 100 million mice are used in biomedical research globally each year
Laboratory mice are housed in small plastic cages, typically 30x15cm, often without enrichment beyond food and water
Mice are highly social, territorial, and active explorers - standard barren housing fails to meet basic behavioral needs
Adding nesting material is the simplest and most impactful enrichment - mice consistently prefer to nest and work for this resource
Mice with nesting material show lower stress hormones, better welfare indicators, and in many experiments, more reproducible results
Environmental enrichment including tunnels, hiding places, and running wheels significantly improve behavioral repertoire
Housing barren cages affects experimental outcomes - stress alters pain responses, drug metabolism, and immune function

Welfare Considerations

Laboratory mouse welfare is a domain where the scale of use (hundreds of millions globally) means even modest improvements have enormous aggregate welfare impact. Standard housing conditions - small, barren plastic cages - deny mice the nesting, burrowing, exploration, and complex social interactions that characterize their natural behavior. Chronic social stress in group-housed animals without adequate resources, or isolation stress in singly housed males, represents ongoing welfare harm that may be unmeasured and unaddressed in most facilities. The scientific argument for enrichment is increasingly compelling - stressed animals produce different research results than calmer, better-housed animals, meaning poor welfare may compromise the scientific value of the research that ostensibly justifies the animals' use.

What You Can Do

Support research institutions that have implemented evidence-based mouse enrichment protocols including nesting material
Advocate for regulatory requirements mandating minimum enrichment standards for laboratory mice
Donate to organizations developing validated enrichment approaches and advocating for their adoption
Engage with universities and research institutions about their mouse welfare programs
Support the development of animal-free research methods that can replace mouse models
Choose personal care and cosmetic products from companies committed to non-animal testing