Laboratory mice are the most widely used research animals globally. Enrichment provision dramatically improves their welfare with minimal impact on research validity.
Laboratory mice housed in barren conditions experience chronic stress that compromises both their welfare and research reproducibility. Provision of nesting material, shelter tubes, and bedding depth sufficient for burrowing represents a minimal refinement with major welfare impact. Some historical resistance to enrichment citing possible confounding effects has been contradicted by research showing enriched mice produce more reproducible and translatable data. Species-appropriate housing is both an ethical obligation and a scientific improvement.