Measuring the validity and clinical applicability of the Facial Assessment Pain score (EQUUS-FAP) and the Composite Pain score (CPS) in assessing somatic pain caused by mild orthopaedic surgical procedures and in horses with acute orthopaedic trauma.

Abstract

Systematic pain assessment in the equine practice has come a long way, but the assessment for the use of these tools in clinical conditions for different grades of orthopaedic pain is lacking, especially for mild pain. As described by Ashley in an earlier review, the ideal grading system is: “linear, weighted, sensitive to pain-type, breed- and species-specific, less dependent on the observer and closed to misinterpretation”. Clinical studies on orthopaedic pain in horses have been presented using Visual Assessment Scores (VAS), Numerical Rating Scores (NRS) and early use of Composite Pain Scales (CPS). Bussières et al. (2008) developed a CPS and validated the system in research settings. The CPS used was a modification on an existing CPS scales, where less sensitive parameters and parameters with low inter-rater scores were removed or modified. A Facial Assessment Pain scale (FAP) isn’t yet used to asses orthopaedic pain. The Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP) has shown repeated an objective scoring op pain in horses with acute colic (Van Loon & Van Dierendonck, 2015). In this study a combination of the CPS and EQUUS-FAP is used. CPS and EQUUS-FAP were graded using live observations of patients admitted to the University Clinic for Horses in Utrecht for orthopaedic surgery or orthopaedic trauma. The group consisted of 54 horses (n=18 surgery patients, n=11 trauma patients an n=25 control animal) and 25 Shetland ponies (n=17 surgery patients and n=8 control animals). Animals were followed for 5 days (on the day before procedure, on the day itself and the three following days). Both systems showed high inter-rater reliability (ICC=0,95 for CPS and ICC=0,90 for EQUUS-FAP, P<0,01). There was a significant difference when comparing the different groups (control vs. orthopaedic patients vs. trauma patients). The scoring systems showed a drop in scores when the pain diminishes in time. The scores showed a drop when comparing data before and after analgesic administration. It was concluded that both systems were reliable as tools to assess acute orthopaedic pain in horses.