Rats and mice make up over 80 percent of laboratory animals globally, and consistent application of the 3Rs framework offers the greatest single opportunity to reduce laboratory animal suffering at scale.
The scale of mouse and rat use in research means that even small improvements in individual welfare translate to enormous aggregate benefit. Social isolation of rodents, which is common in research facilities, causes measurable chronic stress that also compromises research validity by confounding results. Nesting material provision, once considered optional enrichment, is now recognized as a thermoregulatory necessity that significantly reduces cold stress. Pain assessment using grimace scales enables earlier analgesic intervention. The alignment between welfare improvements and research quality — less stressed animals produce more reproducible data — creates a scientific incentive that complements the ethical case for welfare improvement. Advocate for rigorous 3Rs implementation at all institutions conducting rodent research.