Facial Expression Pain Scale (FEPS) for donkeys

Abstract

Assessment of pain in horses is difficult and can only be evaluated by changes in behaviour and physiology as they cannot verbally express their pain. Enough data is collected about facial expressions of pain in horses but there is a hardly any information available about obvious pain expressions shown by the donkey. This study describes the inter-observer reliability, differentiation between patients and control donkeys and condition related behaviour to further develop and improve the Facial Expression Pain Scale (FEPS) for donkeys in acute pain at ‘The Donkey Sanctuary’. This study was performed using 159 donkeys (n=44 patients, n=115 controls). The facial expression pain scores were assessed by 2 observers and followed over time. The patients were categorised by specific types of pain: post-operation pain (n=6), facial pain (n=7), colic (n=7) and lameness (n=24). Cut-off value for the FEPS was determined at 1 to obtain maximal differentiation between patients and healthy control donkeys. The FEPS showed good inter-observer reliability (ICC=0.77 P<0.001) and the FEPS could differentiate between patients and control donkeys (P<0.001). Age, gender, size and social relations were taken into account in choosing the control donkeys, matching the patient’s characteristics but no significant differences were found between the specific control groups and the total control group. A statistical analysis between a specific group of patients and their specific control donkeys showed different results for every subgroup of patients: colic P<0.001, facial pain P<0.01, lameness P<0.001. No significant differences were found between donkeys with post-operative pain and control donkeys (P=0.248). Internal sensitivity and specificity were good for the FEPS for the total patient group (sensitivity 68% and specificity 75%). The FEPS offers an effective and reliable method of assessing various types of acute pain in donkeys. Further studies are necessary to increase the patient data, specifically patients after more invasive surgery, to improve the FEPS even more.