Objective Assessment of Chronic Pain in Horses Using the Horse Chronic Pain Scale (HCPS): A Scale-Construction Study.
Authors: van Loon Johannes P A M, Macri Lucia
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Horse Chronic Pain Scale Development Chronic pain assessment in horses remains challenging despite its critical importance for welfare and management decisions, prompting van Loon and Macri to develop the Horse Chronic Pain Scale (HCPS)—a composite tool combining behavioural observations with facial expression analysis. The researchers evaluated 53 horses (26 with confirmed chronic conditions including osteoarthritis, laminitis, back/neck problems, and dental disorders; 27 healthy controls) across three consecutive daily assessments, with blinded observers scoring behavioural parameters via the Horse Chronic Pain Composite Pain Scale (HCP CPS) and facial expressions using the EQUUS-FAP (Equine Utrecht University Scale for Facial Assessment of Pain). The HCP CPS demonstrated good inter-observer reliability (ICC = 0.84), whilst the facial assessment component showed weaker agreement between observers (ICC = 0.45), though the combined HCPS achieved acceptable reliability overall (ICC = 0.78); the scale successfully differentiated chronically painful horses from controls on two of three assessment days. Whilst these results are encouraging for establishing an objective pain measurement tool, the authors appropriately note that validation in clinical practice remains essential before widespread adoption—suggesting that equine professionals should monitor this work as it develops, particularly given the current limitations in reliably assessing chronic pain conditions that significantly impact management and treatment decisions.
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Practical Takeaways
- •A new objective pain assessment tool combining behaviour and facial expressions has been developed for chronic pain in horses, though further validation is needed before clinical adoption
- •Behavioural observations are more reliable than facial expression assessment alone for identifying chronic pain in horses
- •This scale may help standardise chronic pain evaluation across different horses and conditions, potentially improving welfare assessment and treatment decisions
Key Findings
- •The Horse Chronic Pain Scale (HCPS) demonstrated good inter-observer reliability overall (ICC = 0.78, p < 0.001), with the behavioural component showing good reliability (ICC = 0.84) but facial expression component showing poor reliability (ICC = 0.45)
- •The HCPS successfully differentiated between horses with chronic painful conditions and healthy control animals on 2 out of 3 assessment days (p < 0.05)
- •The study evaluated 53 horses (26 with clinically confirmed chronic pain conditions and 27 healthy controls) assessed daily for three consecutive days by blinded observers