Unusual anomalies of the arteries at the base of the heart in a dog.

Anomalous blood vessels at the base of the heart in a 6-month-old German Shepherd Dog are described. On the right side, the thoracic vertebral artery was absent and the dorsal intercostal arteries to the first 2 ribs arose directly from the deep cervical artery. The right bronchoesophageal artery was exceptionally large and arose from the right costocervical trunk. An anastomosis was present between the fifth dorsal intercostal artery and the left bronchoesophageal artery. On the left side the left bronchoesophageal artery arose from the left pulmonary artery close to the bifurcation of the pulmonary trunk. Anastomoses were present between the third dorsal intercostal artery and the paraconal interventricular branch of the left coronary artery and between the third dorsal intercostal artery and the left bronchoesophageal artery. Radiographically the anastomoses between the dorsal intercostal artery and the left pulmonary artery via the left bronchoesophageal artery could be confused with a patent ductus arteriosus.