ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. Anesthesiology and Animal Pain Management
This article is part of the Research TopicPain Assessment and Management in Veterinary Medicine - Volume IIView all 6 articles
Client-Specific Outcome Measure (CSOM) for Chronic Osteoarthritis Pain Assessment in Horses
Provisionally accepted
Eleonora Benetti1*
Adolfo Maria Tambella2
Sabrina Nathalie Andreis3Stefan Witte4
Caterina Di Bella2
Claudia Spadavecchia1- 1Vetsuisse Faculty, Department of Clinical Veterinary Medicine, Section of Anesthesiology and Pain Therapy, University of Bern, Bern, Switzerland., Bern, Switzerland
- 2Universita degli Studi di Camerino Scuola di Bioscienze e Medicina Veterinaria, Camerino, Italy
- 3Amt für Veterinärwesen, Bern, Switzerland., Bern, Switzerland
- 4Tierklinik Schönbühl AG, Schönbühl Switzerland., Bern, Switzerland
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Osteoarthritis (OA) is a prevalent cause of chronic pain and lameness in horses. Whereas lameness can be quantified using objective measures, the assessment of OA-associated pain remains challenging. This study aimed to evaluate the applicability of the Client-Specific Outcome Measure (CSOM), a tool widely used in small animals, to assess chronic OA pain in horses through caretakers' assessment. Seventeen privately owned horses with confirmed OA were enrolled in a 20-week randomized, double-blind, placebo-controlled study. For each horse, three individual pain-related indicators (CSOM items) were identified through a veterinarian-caretaker consultation. Over the study period, the selected items were regularly scored (0-4) and the scores summed to obtain a total CSOM score (CSOM-sum). The CSOM-sum was then compared with other pain assessment measures: a pain visual analogue scale (VAS) attributed to both the caretaker (VAS-own) and the veterinarian (VAS-exp), subjective lameness scores, and a gait asymmetry index. The CSOM-sum showed moderate but significant correlations with all the other pain and lameness measures (rₛ = 0.49–0.60, p < 0.05). In particular, CSOM-sum correlated with gait asymmetry (rₛ = 0.434, p < 0.0001); subgroup analysis revealed a moderate correlation in treated horses (rₛ = 0.4539, p = 0.0025) and a higher correlation in controls (rₛ = 0.5536, p = 0.0006). The VAS-own and VAS-exp scores showed good overall agreement (bias = –4.76 mm; ICC = 0.727; ICC_T = 0.625; ICC_C = 0.838), although with relatively wide limits of agreement. The internal consistency of the CSOM items was high (Cronbach's α = 0.81 overall; α_T = 0.787; α_C = 0.890). Our findings indicate that the CSOM, provided that relevant items are carefully identified, may represent a valuable complementary tool for assessing and monitoring pain severity in horses under field conditions.
Keywords: Chronic pain 3, Client specific outcome measures 5, CSOM 4, equine 1, osteoarthritis 2, subjective assessment 6
Received: 19 Dec 2025; Accepted: 16 Feb 2026.
Copyright: © 2026 Benetti, Tambella, Andreis, Witte, Di Bella and Spadavecchia. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Eleonora Benetti
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