Mice and rats are the most widely used research animals globally, and refinement advances in housing, handling, and experimental design are improving welfare for millions of individuals.
Laboratory mouse and rat welfare has advanced significantly through refinement research that demonstrates both welfare benefits and reproducibility improvements from better husbandry. Tail lifting — the historical standard for mouse handling — causes measurable acute stress that elevates corticosterone for hours; tunnel handling eliminates this stress and is now standard practice in refined facilities. Environmental enrichment that was historically omitted as potentially confounding experimental results is now recognized as both welfare-improving and reproducibility-enhancing — stressed, deprived animals produce more variable experimental data than animals in enriched, low-stress conditions. The alignment of welfare and scientific quality goals in laboratory animal research is a powerful argument for refinement investment. Progress in pain assessment tools and analgesic protocols means that laboratory animals can now receive more effective pain management than was possible two decades ago.