Advances in mouse pain assessment through facial coding, behavioral testing, and biomarkers are improving the detection and management of pain in one of the most commonly used laboratory species.
Accurate pain assessment in mice is fundamental to adequate welfare management. For decades, pain in mice was either ignored or assessed through behavioral tests that required active animal response, missing passive pain expression typical of prey species. The Mouse Grimace Scale revolutionized assessment by providing a validated measure of spontaneous pain expression that can detect pain without requiring the animal to engage in any task. This has transformed post-operative monitoring and assessment of disease models that cause pain. The development of automated coding using machine learning is making it feasible to assess pain continuously in large numbers of animals without requiring intensive human observation, enabling a new level of welfare monitoring.