Pig Pain Recognition: Closing the Assessment Gap

Recognising pain in pigs is challenging because of their stoic, prey-animal nature. Advances in pain assessment tools are transforming veterinary care and farm welfare.

Key Facts

Pigs suppress pain behaviour in the presence of humans and other potential threats, making pain recognition difficult.
The Pig Grimace Scale (PGS), adapted from the rodent grimace scale, assesses orbital tightening, nose disc flattening, cheek tension, and ear position.
The PGS was validated in castrated piglets and has since been extended to other pain conditions.
Postoperative pain in pigs following castration, tail docking, or surgical procedures is frequently undertreated.
Lameness scoring in pigs provides a behavioural pain indicator that can be assessed routinely during farm walks.
Pigs in pain show reduced social interaction, increased aggression, and altered lying positions.
Pressure algometry measures mechanical pain thresholds and can objectively detect subtle pain states in pigs.
Validated pain assessment tools enable farmers and vets to identify, treat, and monitor pain outcomes in individual pigs.

Welfare Considerations

Pain in pigs has been chronically under-recognised and undertreated, driven by the difficulty of assessment and economic pressure against veterinary treatment. The development and adoption of validated pain assessment tools is transforming this situation: when pain can be objectively demonstrated, the case for treatment becomes much harder to dismiss. Grimace scales and behavioural pain indicators provide practical, farm-applicable tools that do not require specialist equipment. The broader welfare implication is that a pig farm that routinely uses pain assessment tools and provides analgesia for painful procedures is qualitatively different — better — than one that does not, regardless of other management factors. Pain recognition is the gateway to pain treatment, and both are essential components of good welfare.

What You Can Do

Advocate for mandatory pain relief for all painful husbandry procedures in pig farming.
Support the development and adoption of validated pain assessment tools in pig veterinary practice.
Choose pork from welfare-certified systems that require pain management standards.
Support research into species-specific pain assessment and analgesic protocols for pigs.
Encourage pig farmers and vets to adopt the Pig Grimace Scale in routine assessment.
Raise awareness that pain management in farm animals is a welfare necessity, not a luxury.