The Sheep Pain Facial Action Unit System (SPFAS) provides a validated tool for recognising pain in sheep. Its practical application in farm and veterinary settings enables better pain management decisions.
Facial grimace scales represent a significant practical advance in farm animal pain management because they provide an objective, rapid, and non-invasive pain assessment method that can be applied without specialised equipment. Sheep's stoic nature means that behavioural pain signs are subtle and easily missed, particularly in busy farm settings. The grimace scale provides a systematic assessment that reduces reliance on vague impressions. Validation against known painful conditions gives the scale clinical credibility: sheep with footrot, mastitis, or post-surgical pain consistently score higher than healthy controls. The practical challenge is training sufficient farm workers and veterinarians to use the scale reliably; research shows that even brief training significantly improves accuracy. Digital tools that automate scoring using smartphone cameras are in development and could make routine grimace scale assessment feasible in commercial settings.