abnormal bisubclavian trunk arising from the aortic arch determined by cadaver dissection of a native dog: a case report

congenital anomalies of the great thoracic vessels have been reported in 20% of dogs and cats. in some cases, the vascular ring anomalies remain unrecognized throughout the lifetime of an animal. this report describes a case with an unusual vascular ring anomaly (vra) that was detected during dissection on a cadaver of an approximately two-year-old male native mixed breed dog. no history of the animal’s life was available. but, good physical condition and age of the animal based on dentition indicated the anomaly was perhaps asymptomatic. two main branches of the aorta were identified with the initial branch being a bicarotid trunk followed by a bisubclavian trunk. the left subclavian and aberrant right subclavian arteries formed a very short trunk and arose directly from the aortic arch. no dilatation cranial to the esophageal sulcus was found. to the authors' knowledge, our case is the first report of such anomalies perhaps without any clinical signs in a native dog in iran.