Most veterinarians are familiar with the persistent right aortic arch (PRAA), shown here.  A vascular ring is formed by the aortic arch on the right side, with the ligamentum arteriosum dorsolaterally, and the pulmonary artery on the left and ventrally.  This ring compresses the esophagus and trachea, and the resultant swallowing difficulty is relieved by dividing the ligamentum arteriosum surgically.

Other vascular rings may occur during development and surgeons need to know enough aortic arch embryology to identify the abnormal vessels and to address them surgically.  The purpose of this demonstration is to teach you to identify and manage the various types of less common vascular rings you may encounter.