Background: Congenital anomalies of the aortic arch are important to recognize as they may be associated with vascular rings. The most common vascular ring anomaly in dogs is persistent right aortic arch. However, published data of the distribution and percentage of the different types of vascular rings and other aortic arch anomalies are lacking. The objective of this retrospective descriptive study was to characterize the amount and types of aortic arch anomalies that can be detected in thoracic computed tomography (CT) examination in dogs.
Results: Dogs that underwent thoracic CT between 2008 and 2020 were included. A total of 213 CT studies were sampled; 21 dogs (21/213, 9.9%) showed a right aortic arch, and the following additional findings were detected: aberrant left subclavian artery (17/21, 76.2%) branching from the PDA (1/21, 4.8%), left-sided brachiocephalic trunk (3/21, 14.3%), bicarotid trunk (17/21, 81.0%), double aortic arch (1/21, 4.8%). No dog presented right aortic arch without further anomalies. Also, 192 dogs (192/213, 90.1%) showed left aortic arch. The following additional abnormalities were obtained: aberrant right subclavian artery (3/192, 1.6%) without clinical signs of vascular ring, aberrant vessel branching from the aorta into the left caudal lung lobe (2/192, 1.0%), focal dilataion of the left or right subclavian artery (2/192, 1.0%), bicarotid trunk (1/192, 0.5%).
Conclusion: The current study indicates that aberrant left subclavian artery is the most common additional finding in dogs with persistent right aortic arch and that left-sided brachiocephalic trunk can occur in dogs, which was previously unpublished. Aberrant right subclavian artery can be an incidental CT finding without clinical relevance.