Pain Assessment in Pigs: Validated Tools and Welfare Monitoring

Accurate pain assessment in pigs is essential for welfare-appropriate treatment decisions, but validated tools have only recently become available for practical farm use.

Key Facts

Pigs show changes in facial expression during pain analogous to mouse grimace scales — the Pig Grimace Scale (PGS) is now validated for acute pain assessment
Behavioural indicators include reduction in exploration, play and social behaviour, increased isolation and abnormal postures
Lameness scoring systems for pigs use 0-5 or 0-4 scales consistent with cattle locomotion scoring adaptations
Castration without anaesthesia in piglets causes measurable pain responses lasting several hours — welfare regulations are tightening across the EU

Welfare Considerations

Pain assessment in pigs has historically been limited by observer training and the time required for individual animal assessment in intensive settings. Validated tools including the Pig Grimace Scale and composite pain scoring allow more systematic welfare monitoring. The most significant pain welfare problems in pigs include castration, tail docking, teeth clipping, lameness, farrowing injuries and systemic disease — all requiring pain management frameworks that validated assessment tools support. Analgesic treatment of farm pigs remains underused relative to the known prevalence of painful conditions.

What You Can Do

Train farm staff in the Pig Grimace Scale for acute pain assessment after husbandry procedures
Implement mandatory NSAID treatment following castration and tail docking where these procedures are performed
Use locomotion scoring to identify and treat lame pigs promptly before chronic pain becomes established
Advocate for EU-wide elimination of routine castration without anaesthesia by 2030 transition targets