Welfare of Laboratory Mice Enrichment

Laboratory mice are the most widely used research animals globally and enrichment of their housing to support natural behaviour is a critical welfare requirement.

Key Facts

Approximately 100 million mice are used in research globally each year
Standard laboratory housing in IVC cages provides minimal environmental complexity
Nest material provision is considered essential basic enrichment for mice and reduces stress hormones
Running wheels provide exercise enrichment with measurable welfare benefits
Burrowing substrate meets a highly motivated natural behaviour in wild mice
Social housing of compatible mice is welfare-superior to individual housing for most research purposes

Welfare Considerations

Laboratory mouse welfare is a welfare issue of enormous scale given the numbers involved globally. Basic enrichment including nesting material, running wheels and burrowing substrate significantly improves welfare outcomes measurable through physiological, behavioural and health parameters. Providing enrichment in laboratory settings was historically resisted due to concerns about experimental variation, but evidence shows that enriched housing often produces more scientifically valid and reproducible results by reducing the abnormal baseline physiology associated with impoverished housing. The 3Rs principle of refinement explicitly requires that housing and enrichment meet animals' needs.

What You Can Do

Support the NC3Rs and equivalent organisations funding laboratory animal welfare research
Advocate for enrichment standards to be embedded in all institutional animal care policies
Engage with research institutions about their laboratory animal welfare standards
Support refinement research that identifies housing improvements compatible with scientific validity