Identification of common equine cardiac murmurs

Cardiac murmurs are commonly identified in horses as either an incidental finding during elective clinical examinations or when an animal is presented with clinical signs that may be consistent with cardiac disease; for example, poor performance evaluation and ventral subcutaneous oedema. To assess the significance of the identified murmur, the clinician needs to determine whether it is associated with normal physiological or pathological blood flow and, if the latter, whether it is likely to affect cardiac function and cause clinical signs. Of particular significance in equine cardiology compared to other companion animals is whether the horse is at risk of sudden death – an important consideration for rider safety. The answer to the majority of these questions can be obtained from a combination of a thorough clinical examination and meticulous auscultation. This article gives a brief guide to the cardiac cycle, describes how to perform a cardiovascular examination and discusses the common murmurs in adult horses and their significance.