The blood supply to the head, neck, thorax and thoracic limb come from the aorta artery through its two broad branches, the brachiocephalic trunk and the left subclavian artery, which arise from the arch of the aorta. The present report described the abnormal origins of the right subclavian and common carotid arteries observed in eigth dogs, during the last twenty years of dissection in anatomy classes. All these eight cases presented three large arteries that left the aortic arch. The first one to arise was a trunk for both common carotid arteries, then a left subclavian artery and finally a right subclavian artery. The bicarotid trunk was originated from the aortic arch at the left side of the trachea and course cranially towards the first rib, where it bifurcated into the right and left common carotid arteries. Following the left subclavian artery arose and after that the right subclavian artery, which arose directly from the aortic arch. This vessel ran towards the first rib and crossed the median plane at the dorsal aspect of the esophagus and the trachea. Both right and left subclavian arteries emitted the usual branches. Although the esophagus was indented by the anomalous vessel, the absence of a cranial dilatation around the sulcus and the good nutritional condition of the animals lead to a conclusion that the swallowing was not significantly affected.
aortic arch; subclavian artery; Canis familiaris
