Relevance of an equine pain face scale in evaluating pain after routine castration

Abstract

INTRODUCTION There are currently many equine pain evaluation techniques. For objective judgement measurable parameters such as heart and respiratory rate, temperature and peristalsis as well as blood parameters are verified. It is known that heavy pain results in elevation of the heart rhythm, serum cortisol and reduction in locomotion. However these parameters are influenced by many factors other than pain, hence most of the pain assessment scales focus on changes of behaviour, stance or movement in evaluating visceral, orthopedic, teeth and other types of pain. Signs considered in these scales undoubtedly determine the assessment of the patients’ condition and correct diagnosis in critical cases such as colic. On the other hand, the horse as a prey animal is prone to hide signs of sickness. That is why indications of pain might be very subtle and hard to notice in medium grade pain, which is evaluated in assessing animals’ well-being and effectiveness of analgesia after a surgical operation. Humans have a capability of recognising facial expressions of one another and even when trying to hide ones’ pain facial expression changes. It is estimated that this property is present in animals as well, especially ones living in herds such as horses. AIM Our aim was to evaluate the relevance of equine face expression in addition to behavioural changes, heart and respiratory rates in identifying post-castrational pain. METHODS 9 horses brought to LUHS Large Animal Clinic for routine castration were included in the study. Procedures were performed by the same surgeon team and using the same anesthesia protocol. Every patient was examined five times: before the procedure, 1 hour and 6 hours after the procedure,the next day and on the 3rd day. Behavioural ques observed included activity, pose, head position, attention to the painful area, interaction with the observer, response to feed and pain related actions such as pawing. [...].