Left aortic arch and right ligamentum arteriosum causing esophageal obstruction in a dog.

A 10-week-old, mixed-breed dog was examined because of persistent regurgitation. Results of thoracic radiography and fluoroscopy of the esophagus, using a liquid suspension of barium sulfate, were suggestive of a vascular ring anomaly. During left lateral thoracotomy, a left aortic arch was identified, but the cause of the esophageal obstruction could not be determined. Results of endoscopic examination of the esophagus suggested a compressive lesion originating from the right side of the esophagus. An anomalous artery could not be identified on an aortogram. Post-mortem examination revealed a left aortic arch and right ligamentum arteriosum that were causing the esophageal obstruction.