Mice are the most widely used laboratory animal. Improving pain recognition and management in mice is one of the highest-impact welfare refinements in biomedical research globally.
Mice used in research experience pain from experimental procedures, surgery, disease models, and husbandry practices. Despite the Mouse Grimace Scale providing a validated, non-invasive pain assessment tool since 2010, its use in research facilities remains inconsistent. Concerns that analgesics will confound experimental results have led to widespread under-treatment of pain — but evidence shows that untreated pain itself confounds results through stress-induced physiological changes. Male researchers have been found to stress mice through their scent, highlighting how subtle welfare impacts can compromise both animal welfare and research quality. Comprehensive pain management protocols, including pre-emptive analgesia for surgical procedures, represent a refinement that simultaneously improves welfare and research validity.