Pain recognition and management in laboratory animals has improved dramatically through the development of species-specific grimace scales and better analgesic protocols. Understanding these advances drives better practice.
Laboratory animal pain management is one of the most significant advances in research animal welfare in recent decades. Before grimace scales, pain assessment relied on subjective observer impression that proved unreliable and inconsistent. Validated facial action coding systems — identifying specific muscle movements associated with pain — provide objective, consistent measures that any trained observer can apply. The Mouse Grimace Scale (MGs) showed that conventional surgical procedures caused significantly more pain and for longer than previously recognized. Post-operative analgesic protocols have improved dramatically as a result. Importantly, controlling pain also improves data quality — pain activates stress hormones that confound many experimental outcomes, making analgesic use scientifically as well as ethically justified.