Laboratory mice and rats are the most numerous research animals globally; welfare refinements in housing, handling, and procedures have significant cumulative impact.
Laboratory rodent welfare has improved substantially through refinement — small changes in handling, housing, and procedure that cumulatively reduce suffering without compromising scientific validity. Tunnel handling reduces acute stress; social housing improves psychological wellbeing; environmental enrichment reduces abnormal behavior; and alternative euthanasia methods eliminate CO2 distress. These refinements are individually modest but collectively significant across the hundreds of millions of rodents used in research annually. The refinement approach — improving welfare within existing research frameworks — complements the longer-term replacement goal and is actionable immediately.