Morphology of the aortic arch branching pattern in raccoon dogs (Nyctereutes procyonoides, Gray, 1834)

Abstract

Background Aortic arch (AA) branching patterns vary among different mammalian species. Most previous studies have focused on dogs, whereas those on raccoon dogs remain unexplored. Objectives The objective of this study was to describe the AA branching pattern in raccoon dogs and compare their morphological features with those of other carnivores. Methods We prepared silicone cast specimens from a total of 36 raccoon dog carcasses via retrograde injection through the abdominal aorta. The brachiocephalic trunk (BCT) branching patterns were classified based on the relationship between the left and right common carotid arteries. The subclavian artery (SB) branching pattern was examined based on the order of the four major branches: the vertebral artery (VT), costocervical trunk (CCT), superficial cervical artery (SC), and internal thoracic artery (IT). Results In most cases (88.6%), the BCT branched off from the left common carotid artery and terminated in the right common carotid and right subclavian arteries. In the remaining cases (11.4%), the BCT formed a bicarotid trunk. The SB exhibited various branching patterns, with 26 observed types. Based on the branching order of the four major branches, we identified the main branching pattern, in which the VT branched first (98.6%), the CCT branched second (81.9%), the SC branched third (62.5%), and the IT branched fourth (52.8%). Conclusions The AA branching pattern in raccoon dogs exhibited various branching patterns with both similarities and differences compared to other carnivores.