The Rat Grimace Scale provides a validated tool for assessing pain in laboratory rats through facial action coding, improving welfare by enabling objective pain detection and treatment decisions.
The Rat Grimace Scale represents a significant advance in laboratory animal welfare by providing a non-invasive, objective method for pain assessment. Before validated grimace scales, pain recognition in laboratory animals depended on behavioral changes that could be subtle, species-specific, and easily missed by untrained observers. The grimace scale allows any trained observer to assess pain state quickly and reliably, enabling prompt analgesic treatment. Integration of grimace scale assessment into routine post-operative monitoring protocols is a welfare improvement that has the support of strong scientific evidence. Its implementation across research institutions remains uneven, representing an achievable welfare gain that requires only training and institutional commitment.