Mice and rats are the most commonly used research animals globally — their welfare improvements have been among the most evidence-based in animal research.
Laboratory mouse and rat welfare has improved substantially over recent decades through systematic application of welfare science. Enrichment — nesting material, shelters, social housing — is now standard in well-run facilities and demonstrably reduces stress. Handling technique affects both animal welfare and experimental outcomes, with stress-minimizing methods now validated and recommended. Refinement of experimental endpoints, housing conditions, and analgesic use continues to advance through dedicated welfare science research. Despite these improvements, the sheer scale of rodent use means that aggregate welfare impacts remain enormous, and investment in replacement alternatives continues to be justified.