Performance of four equine pain scales and their association to movement asymmetry in horses with induced orthopedic pain.
Authors: Ask Katrina, Andersen Pia Haubro, Tamminen Lena-Mari, Rhodin Marie, Hernlund Elin
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Determining the true extent of a horse's pain remains one of equine practice's most persistent challenges, particularly when subtle lameness is present. Ask and colleagues compared four validated facial and behavioural pain assessment tools—the Horse Grimace Scale, EQUUS-FAP, Equine Pain Scale, and Composite Orthopedic Pain Scale—alongside objective movement analysis during trot in horses experiencing experimentally induced reversible arthritis. The researchers used intraclass correlation coefficients to establish inter-rater reliability and area under the curve analysis to evaluate each scale's diagnostic accuracy in detecting pain-related movement asymmetry. Their findings revealed varying levels of agreement between raters and inconsistent correlations between pain scores at rest and the degree of lameness observed during locomotion, suggesting that no single pain scale reliably predicts movement dysfunction across all cases. For practitioners, this emphasises the importance of combining multiple assessment methods rather than relying on any single observation tool, and reinforces that static pain evaluation does not necessarily reflect functional impairment during work—meaning lameness evaluation during movement remains essential despite investment in rest-based pain scales.
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Practical Takeaways
- •Use standardized pain scales to objectively assess orthopedic pain at rest alongside movement evaluation for comprehensive lameness assessment
- •Facial grimace scales and composite pain scales offer measurable, reproducible methods for pain evaluation in clinical practice
- •Movement asymmetry during trot correlates with resting pain indicators, supporting use of integrated pain and gait assessment protocols
Key Findings
- •Four pain scales (HGS, EQUUS-FAP, EPS, CPS) were evaluated for reliability and diagnostic accuracy in horses with induced acute arthritis
- •Reliability assessed using intraclass correlation coefficients (ICC) and diagnostic accuracy using area under the curve (AUC)
- •Relationship between resting orthopedic pain and degree of movement asymmetry during trot was investigated