Diesel presented to PVESC after being diagnosed with a suspect PRAA (persistent right aortic arch). He was 14 weeks old, and weighed only 18 pounds. He had been with his owner for only a month. He was skinny, and although he had a tremendous appetite, could not keep food down. His primary veterinarian was suspicious of a congenital vascular abnormality, called PRAA, that could be causing esophageal compression. A CT scan confirmed the presence of a right sided aortic arch, causing compression and strangulation of the esophagus.
When puppies are developing in utero, their blood is oxygenated by the mother, not by their lungs. Special shunting blood vessels around the heart allow blood to bypass the fetal lungs. Once puppies take there first breath, these shunting vessels typically close. When the vessels fail to close, it can result in a condition called patent ductus arteriosus.
In normal fetal development, the aorta develops to the left of the esophagus, and the trachea is just beneath the esophagus at the level of the base of the heart. The pulmonary artery is also on the left and just below the aorta. A vessel called the ductus arteriosus connects the 2 large vessels (aorta and pulmonary artery). All of these structures are left-sided, and as a result, do not constrict the esophagus as it passes next to the heart base.
In the patient with a PRAA, the aortic arch develops on the right side. Over the base of the heart, the esophagus is entrapped by the trachea on the right, the aorta on top, the right pulmonary artery on the left and the ductus arteriosus (the vessel connecting the pulmonary artery and the aorta). This entrapment constricts the esophagus so that solid food cannot pass down into the stomach. The esophagus gets stretched out, puppies are unable to swallow food, and unable to gain weight and thrive. These patients are at risk of aspiration pneumonia as well.