Clinical Assessment of Pain in Horses with Colic using Composite Pain Scale and Horse Grimace Scale

The current study evaluated two pain assessment measures in horses with colic: (1) the Composite Pain Scale (CPS), which assesses overall clinical (behavioural and physiological) pain, and (2) the Horse Grimace Scale (HGS), which examines changes in pain-related facial expressions. A total of 30 horses with a clinical diagnosis (based on clinical signs) of colic were tested over four days of treatment. Pain evaluation was used to divide colic in horses into mild, moderate and severe pain groups according to severity. The control group consisted of eight clinically and apparently healthy horses. CPS scores differed significantly between pain groups (p < 0.01), with horses experiencing severe pain having the highest score, followed by moderate and mild pain. HGS scores were considerably higher (p < 0.01) in horses experiencing moderate to severe pain. Both pain scores in colic-affected horses decreased gradually throughout the therapy period. These findings imply that the CPS is an effective and objective tool for assessing and monitoring the degree of acute pain associated with equine colic. The HGS may provide further information on pain-related facial (expression) changes and can complement clinical pain assessment. These measures may support veterinarians in assessing pain severity, monitoring changes during treatment and improving pain management in horses with colic.