Laboratory mice are the most commonly used mammalian research species, and enrichment refinements improve their welfare while often improving research quality.
Laboratory mouse welfare has improved substantially over the past two decades as the scientific community recognized both the ethical imperative and the research quality benefit of enrichment provision. The common objection — that enrichment confounds experimental results — is largely contradicted by evidence showing that enriched, socially housed mice produce more consistent, reproducible behavioral data than isolated, impoverished animals. The 3Rs framework requires applying the best available welfare refinements, and for mice this includes nesting material, social housing, and appropriate environmental complexity as standards rather than exceptions.