Objective assessment of acute pain in foals using a facial expression-based pain scale.
Authors: van Loon, Trindade, da Silva, Keus, Huberts, de Grauw, Lanci
Journal: Equine veterinary journal
Summary
# Editorial Summary: Facial Expression Pain Assessment in Foals Accurate pain assessment in foals remains challenging in clinical practice, where behavioural and physiological indicators can be subtle or variable. Researchers from Utrecht University have now validated the EQUUS-FAP FOAL scale—a facial expression-based pain assessment tool—through a prospective, blinded case-control study of 100 foals (38 with acute pain conditions and 62 healthy controls), with videos scored by two independent observers to determine reliability and diagnostic accuracy. The scale demonstrated strong inter- and intra-observer agreement (ICC coefficients of 0.85 and 0.90 respectively), and importantly, foals with acute pain scored significantly higher (median 7 out of a maximum score) than controls (median 2.5), with scores declining meaningfully after analgesic treatment—indicating the tool's responsiveness to genuine pain and treatment effects. Using a cut-off score of ≥4, EQUUS-FAP FOAL achieved 88% sensitivity and 88% specificity with 95% diagnostic accuracy, suggesting reliable identification of painful foals in clinical settings. For practitioners managing neonatal and young foals, this validated facial expression scale offers an objective, rapid assessment method that requires only brief video footage and could improve early pain recognition and guide timely intervention before pain becomes more entrenched.
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Practical Takeaways
- •EQUUS-FAP FOAL is a reliable and practical tool for objectively assessing acute pain in foals using facial expression analysis, with high sensitivity and specificity
- •A pain score of 4 or higher indicates likely acute pain in foals; scores below 4 suggest absence of significant pain
- •This assessment method can be applied in the field (requiring only brief video recording) and responsiveness to analgesics can be monitored objectively
Key Findings
- •EQUUS-FAP FOAL demonstrated good inter-observer reliability (ICC 0.85) and intra-observer reliability (ICC 0.90)
- •Patients had significantly higher pain scores (median 7) compared to controls (median 2.5, p<0.001)
- •Pain scores decreased significantly after analgesic treatment (median 6.5 to 4.5, p<0.05)
- •Scale achieved 88.2% sensitivity and 87.9% specificity with AUC of 94.9% at cut-off value ≥4