Unusual vascular ring in a cat: left aortic arch with right ligamentum arteriosum.

A young kitten was presented with regurgitation of food at weaning. Episodes of respiratory distress and cyanosis were also present. The cause of food regurgitation was a perioesophageal vascular ring caused by left descending aorta and a right ligamentum arteriosum. This type of vascular ring has not previously been described. There was also anomalous development of the right subclavian artery and a large ventricular septal defect. The respiratory distress and cyanosis was most probably caused by a combination of tracheal compression by the vascular ring and a polycythaemia associated with the ventricular septal defect. Surgical correction was not attempted.