Aortic injection study in a dog with a ductus diverticulum (DD) and three branches from the aortic arch. The proximal two are left and right common carotid arteries (CC). The distal branch is the right or left subclavian artery (SA).

Continued aortic injection study in the dog with a ductus diverticulum. Note persistent contrast in the diverticulum (DD) which indicates that there is no flow through a patent ductus arteriosus. Ventral tracheal deviation (T) supports the likelihood of compression by a retroesophageal subclavian artery (SA).