Pain Recognition in Pigs: Assessment and Management

Recognising and Managing Pain in Pigs

Pain recognition in pigs is a significant welfare challenge — pigs, as prey animals, have evolved to mask pain and vulnerability. This evolutionary behaviour means obvious distress signals often only appear when pain is severe. Developing reliable pain recognition tools and implementing effective pain management are priority areas in pig welfare science and practice.

Why Pain Recognition Matters

Pain causes suffering — that is its defining characteristic as a welfare problem. In pigs, unrecognised and untreated pain causes: reduced feed intake (with production consequences), altered behaviour, impaired immunity, and chronic welfare compromise. Pain during routine husbandry procedures (castration, tail docking, disbudding, processing) is a well-documented welfare concern that legislative and industry standards increasingly address.

Behavioural Indicators of Pain in Pigs

Pain manifests through subtle behavioural changes that require observer training to recognise reliably:

• Posture: Hunched or arched back, reluctance to stand, abnormal lying position (guarding painful area)
• Locomotion: Reduced movement, abnormal gait, reluctance to bear weight on painful limb
• Activity and social behaviour: Withdrawal from group, reduced social interaction, reduced play in younger animals
• Feed intake: Reduced or absent feeding, reduced water intake
• Vocalisation: High-pitched, frequent squealing in acute pain; less useful in chronic pain as pigs may become silent
• Attention to pain site: Biting, rooting, or scratching at affected area

Validated Pain Scales

Composite pain scales for pigs are now being validated and implemented in research and clinical settings. The UPSS (Unesp-Botucatu Pig Composite Scale) and similar instruments score multiple behavioural and postural indicators to provide a total pain score. These tools improve consistency of pain assessment between observers and enable monitoring of analgesic treatment response.

Facial Pain Assessment

Porcine grimace scales — adapted from validated grimace scales in rodents and other species — assess orbital tightening, nose bulge, cheek tension, and ear position as pain indicators. Validation work is ongoing; these tools have particular promise for automated image-based pain monitoring in production settings.

Pain Management in Practice

NSAIDs (meloxicam) are the primary analgesics used in pigs, with good evidence for efficacy in lameness, castration pain, and post-surgical pain. Meloxicam is licensed in pigs in the EU. Local anaesthesia (lidocaine) for castration and disbudding reduces acute procedure pain significantly. Opioids have limited practical use in farm settings but are appropriate for severe pain under veterinary care. Analgesic protocols should be part of all herd health plans.

This page is part of the Animal Welfare Hub — providing evidence-based information to improve the lives of animals. Return to home.