Echocardiographic Detection of a Dissecting Aortic Root Aneurysm in a Thoroughbred Stallion

A 12‐year‐old Thoroughbred stallion was referred with a history of acute pain and tachycardia immediately after breeding a mare. On presentation, the horse showed no evidence of pain and routine examination of the abdomen failed to yield any abnormalities, however, a persistent tachycardia remained. A base‐apex ECG examination revealed sustained ventricular tachycardia which resolved spontaneously within 12 hours of hospitalization. During this period, the stallion developed a grade 4/6 heart murmur. An aortic root aneurysm in the right sinus of Valsalva was diagnosed using two‐dimensional echocardiography. Pulsed‐wave Doppler evaluation revealed turbulent flow within the aneurysm. Repeat echocardiographic examination 10 months after the onset of signs revealed no change and the horse continues to perform as a breeding stallion.