Environmental enrichment for laboratory mice has a strong evidence base demonstrating welfare benefits across multiple domains, and its provision is increasingly required by regulatory frameworks worldwide.
Mouse environmental enrichment research has produced one of the strongest evidence bases in laboratory animal welfare science. The cumulative evidence from hundreds of studies shows consistent welfare benefits from nesting material, shelter, and social housing — reduced stereotypic behavior, lower stress hormones, better immune function, and improved reproductive success. The science has been translated into regulatory requirements in the EU and is reflected in guidelines globally. Yet implementation and compliance vary significantly between institutions, and enrichment quality often remains minimal despite requirements. The scientific case for enrichment has also addressed the concern that enriched environments confound research results: the opposite is true — enriched mice produce less variable, more reproducible data because their stress levels are lower and more consistent. Enrichment is simultaneously a welfare and scientific quality imperative.