May 2012


By: Dustin Weaver, DVM, MPH

Rocky was presented to the San Juan Veterinary Hospital for vomiting and weight loss after being weaned from his mother. Rocky was an eight week-old Norwegian Elkhound/Shepherd mix from New Mexico. Shortly after starting solid foods Rocky began regurgitating (vomiting undigested food before the food goes to the stomach). Because he was not eating, Rocky started loosing weight. Dr. Farrah decided to perform contrast chest x-rays of Rocky using barium (see image below) and idenfified an outpicketing or diverticulum in a portion of the esophagus close to the heart. The diagnosis based on Rocky's breed, age, clinical signs, and images was a group of congenital anomalies called vascular ring anomalies. The most common vascular ring anomaly is a persistent fourth right aortic arch. And now for a lesson in embryology!

The primitive heart tube in a fetus must accomplish the very complicated task of becoming a four chambered and pumping unit while still moving blood throughout the fetus. The primordial aorta originally anchors the heart tube with a series of aortic arches that ultimately fuse to become the great vessels of the heart. For example the third arch becomes the two carotid arteries. The left fourth is morphed into the aorta and the right fourth arch becomes the subclavian artery. Unfortunately, there is an anomaly wherein the fourth arch persists along with the subclavian artery. It forms an abnormal connection between the subclavian artery, pulmonary artery, and the aorta (see image). The esophagus travels through this area and becomes compressed between the 4th right aortic arch, pulmonary artery and aorta. For Rocky this became a problem when he started solid food.

To correct the congenital anomaly chest surgery was required; usually accomplished with the skillful hands of a specialist, but Rocky's owner was financially limited and could not afford the surgery. Ultimately, his owner decided to euthanize. Whether by fate or timing, Dr. Weaver did not have the heart to euthanize Rocky that day especially with a treatment that carried a prognosis for full recovery and requested that the owner relinquish the puppy to San Juan Veterinary Hospital. The wonderful clients, family, and community of Pagosa rallied around Rocky - the surgery was financed! Dr. Farrah, Dr. Weaver, and staff performed their first persistent right aortic arch surgery and not long after Rocky was swallowing solid food and was easily adopted to caring clients.


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