Lab Mouse Environmental Enrichment

Evidence for the welfare benefits of environmental enrichment for laboratory mice and how to implement it.

Key Facts

Mice in bare cages show higher stress hormones, stereotypic behaviors, and reduced immune function
Standard enrichment includes nesting material, shelter tubes, and gnawing material
Nesting material is the single most welfare-significant enrichment for laboratory mice
Enriched mice show reduced variability in research outcomes, improving scientific reproducibility
Social housing is essential — singly housed mice show chronic stress responses
Most major animal care guidelines now require environmental enrichment for laboratory mice

Welfare Considerations

Laboratory mouse enrichment is one of the best-evidenced areas in animal welfare science. The welfare benefits of nesting material, shelter, and gnawing objects for mice are documented across hundreds of studies. Nesting material in particular allows expression of the highly motivated nest-building behavior that mice show regardless of temperature, and its absence causes measurable welfare harm. The scientific case for enrichment extends beyond welfare: enriched mice show more robust, reproducible results because their baseline physiology and behavior is more normal. Enrichment is both a welfare requirement and a scientific best practice for mouse research.

What You Can Do

Advocate for standardized enrichment provision including nesting material as a minimum for all laboratory mice
Support institutional animal welfare committees that enforce enrichment requirements for rodents
Encourage research into which enrichment elements are most welfare-effective for laboratory mouse strains
Engage with animal research ethics training that presents enrichment as both welfare and scientific requirement
Support the 3Rs principle that refinement of mouse housing is an ongoing responsibility, not a completed task