Pig Pain Recognition: Advancing the Science of Porcine Pain Assessment

Accurate pain recognition in pigs is fundamental to welfare monitoring and treatment decisions — validated assessment tools are transforming the ability of farmers and veterinarians to identify and manage pig pain.

Key Facts

The Pig Grimace Scale (PGS), validated in 2019, uses facial action units to score pain in pigs with high inter-rater reliability
Pigs with lameness, wounds, and post-surgical pain show measurable and consistent facial expression changes
Automated machine learning analysis of pig facial expressions can detect pain states with accuracy comparable to trained human raters
Vocalization analysis — particularly high-pitched calls — provides a complementary pain indicator to facial expression
Lameness scoring in pigs remains the most widely used welfare indicator but has lower sensitivity than facial expression tools

Welfare Considerations

Pig pain recognition has advanced dramatically with the validation of the Pig Grimace Scale and the development of automated facial expression analysis. These tools enable objective, consistent pain assessment that can be integrated into routine farm monitoring without requiring individual pig handling. The welfare implication is significant: conditions previously undertreated because pain was not recognised — joint infections, respiratory disease, foot conditions — can now be identified earlier and treated more effectively. Widespread adoption of validated pain assessment tools on pig farms is a high-priority welfare intervention.

What You Can Do

Support training programs that teach farmers and veterinarians to use validated pig pain assessment tools
Advocate for pig pain assessment to be included as a mandatory element of farm welfare auditing
Donate to animal welfare science institutions developing automated pig pain monitoring technology