Validation of the composite pain scale (CPS) for acute colic in horses and the influence of horse personality in responses to pain scored by CPS

Abstract

Currently no standard pain severity scale for acute abdominal pain (colic) in horses is in clinical use. In this study 25 colic patients and 25 control horses have been scored by two independent observers using the CPS after admittance in referral clinic. Sensitivity and specificity of CPS for differentiation between colic horses (pain) and control horses (no pain) are resp. 96% and 84%. Statistics on CPS show a high inter-observer reliability significant on a P<0,001 level. The CPS scores were compared to the scores of the same horses by means of a Visual Analogue Scale (VAS). The VAS scores are determined by two independent experienced veterinarians. VAS has been used as current standard in this experiment. Sensitivity and specificity for this scale are lower than those obtained for the CPS resp. 57% and 60%. Furthermore the inter-observer reliability showed less correlation than for CPS. A low significant correlation is demonstrated between CPS and VAS (P=0,021). CPS seems to be more useful than VAS to assess pain in horses having acute colic. The Composite Pain Scale (CPS) is a promising tool for assessing abdominal pain in horses. Besides the validation of the CPS, the influence of personality of individual horses on the CPS scores is investigated in this study. Horse personality is assessed by questionnaires completed by handlers of the horse and by a few behavioral tests performed by two students on the second day after the horse arriving at the clinic. It was expected that proactive horses would score higher on CPS based on more behavioral expression of pain compared to reactive horses. Not enough data were collected to statistically analyze these data. More research should be done after this subject.