Development and preliminary validation of a pain scale for ophthalmic pain in horses: The Equine Ophthalmic Pain Scale (EOPS).
Authors: Ortolani F, Scilimati N, Gialletti R, Menchetti L, Nannarone S
Journal: Veterinary journal (London, England : 1997)
Summary
# Equine Ophthalmic Pain Scale: A New Clinical Tool for Assessing Ocular Pain Recognising and quantifying ocular pain in horses remains challenging because affected animals cannot communicate their discomfort directly, yet accurate pain assessment is essential for determining treatment efficacy and welfare outcomes. Researchers in Italy developed and preliminarily validated the Equine Ophthalmic Pain Scale (EOPS)—a composite scoring system combining behavioural, physiological and ocular expression indicators—by assessing eight horses with ocular or adnexal disease before and after treatment, alongside 15 healthy controls, with all assessments video-recorded and scored by seven blinded observers. The EOPS demonstrated strong inter- and intra-observer reliability (intraclass correlation coefficients ≥0.75 for most items), good internal consistency (Cronbach's alpha 0.76), and excellent discriminatory ability between healthy and painful eyes (AUC 0.918), with 81.3% sensitivity and 100% specificity when using a total score cut-off of ≥7 to identify ocular pathology. Pain scores significantly decreased following medical or surgical treatment, confirming the scale's responsiveness to clinical change and its potential utility as an objective monitoring tool. Whilst the EOPS shows promise for practice, several behavioural and physiological parameters require refinement, meaning further development and validation across larger populations and diverse ocular conditions would strengthen its clinical application in equine practice.
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Practical Takeaways
- •A validated composite pain scale for equine ocular pain is now available to standardize pain assessment in horses with eye diseases, improving consistency of clinical evaluations
- •The EOPS can reliably distinguish healthy horses from those with ocular pathology using specific behavioural and ocular expression indicators, aiding clinical diagnosis
- •While the scale shows promise, practitioners should be aware that some items require further development; future revisions will likely improve sensitivity for mild pain cases
Key Findings
- •The Equine Ophthalmic Pain Scale (EOPS) demonstrated excellent inter- and intra-observer reliability (ICC ≥0.75) for most behavioural and ocular expression items
- •EOPS total scores differed significantly between healthy controls and horses with ocular pathology at baseline (P<0.001) and decreased post-treatment (P=0.017), indicating responsiveness
- •EOPS achieved 81.3% sensitivity and 100% specificity for identifying horses with ocular pathology using a cut-off score of ≥7, with AUC of 0.918
- •Four items (overall behaviour, position inside box, ear movements, head position) and physiological parameters showed sub-optimal reliability and require refinement