Pressure algometry to quantify muscle pain in racehorses with suspected sacroiliac dysfunction.
Authors: Varcoe-Cocks K, Sagar K N, Jeffcott L B, McGowan C M
Journal: Equine veterinary journal
Summary
# Pressure Algometry for Quantifying Muscle Pain in Racehorses with Suspected Sacroiliac Dysfunction Sacroiliac dysfunction (SID) is common in racehorses but has historically lacked objective assessment tools beyond clinical palpation and subjective pain scoring. Varcoe-Cocks and colleagues evaluated whether pressure algometry—a technique measuring mechanical nociceptive thresholds (MNT)—could provide repeatable, objective quantification of musculoskeletal pain in horses with suspected SID. Two studies were conducted: first, repeatability testing at four anatomical sites in the thoracolumbar and pelvic regions of 12 Thoroughbreds in training; second, correlation analysis in 15 racing Thoroughbreds classified as normal, mildly, moderately, or severely affected by SID, with measurements compared against manual palpation scores. Horses with suspected SID demonstrated significantly lower mean MNTs and greater left-right asymmetry in algometer readings compared to unaffected controls, with particularly pronounced differences in the pelvic region. Critically, MNT values correlated significantly with both SID severity grades and subjective pain responses during palpation, establishing pressure algometry as a reliable, objective measure. For practitioners managing performance horses, this technique offers a repeatable tool to quantify baseline musculoskeletal pain, monitor response to physiotherapy or farrier interventions, and track recovery—addressing a longstanding gap in objective pain assessment for equine orthopaedic conditions.
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Practical Takeaways
- •Pressure algometry offers an objective, repeatable method to quantify musculoskeletal pain in horses, providing an alternative to subjective palpation alone for assessing sacroiliac dysfunction
- •Lower pressure thresholds and side-to-side asymmetry detected by algometry can help confirm clinical suspicion of SID and monitor response to physiotherapy or treatment interventions
- •This technique enables practitioners to document pain objectively, track changes over time, and make evidence-based decisions about treatment efficacy in horses with suspected SID
Key Findings
- •Pressure algometry provided repeatable measurements of mechanical nociceptive thresholds (MNT) at anatomical sites in the thoracolumbar and pelvic regions
- •Horses with suspected sacroiliac dysfunction had significantly lower mean MNT compared to control horses, particularly in the pelvic region
- •Mean pressure algometry measurements correlated significantly with clinical SID grade and subjective muscle pain scores on manual palpation
- •Horses with suspected SID showed greater asymmetry (left-right differences) in algometer measurements compared to control horses