Diagnosis of Persistent Right Aortic Arch with an Aberrant Left Subclavian Artery using CT in a Poodle Dog

A 6-month-old, female poodle presented with a three-month history of persistent regurgitation immediately after eating. On physical examination, the patient was emaciated and dehydrated. Thoracic radiography showed ventral displacement of the trachea and increased radiopacity in the mediastinum, cranial to the heart base. A severely dilated esophagus was identified cranial to the heart on esophagram. Computed tomography (CT) revealed the esophagus was filled with gas, fluid and a little of contrast and dilated from caudo-cervical to cranio-thoracic part. The esophageal diameter was markedly decreased at the heart base. In addition, the trachea was displaced to the left-ventral side of the right aortic trunk and an aberrant left subclavian artery originating from the aorta was identified. There was no evidence of abdominal vascular anomaly. Based on diagnostic imaging, persistent right aortic arch (PRAA) with an aberrant left subclavian artery was diagnosed. The patient did not undergo surgery and died at 15 days after diagnosis. This report describes imaging diagnosis, including CT and radiography in a weaned dog with regurgitation due to esophageal obstruction by PRAA. When PRAA is suspected and conventional radiography or contrast study is insufficient for diagnosis, CT may be helpful for diagnosing PRAA.