A preliminary study of tracheal morphology in mixed-breed dog cadavers: Anatomical variation of tracheal cartilaginous rings

Anatomical abnormalities of the trachea leading to respiratory distress. Few reports describe the morphological characterization of the dog’s trachea, particularly in the tracheal cartilaginous rings. In this study, twelve tracheas from mixed-breed dog cadavers were obtained to investigate their features across three anatomical tracheal regions: cervical, thoracic inlet, and intrathoracic trachea. The average length of the trachea was 18.92 ± 0.67 cm. Each trachea contained a different number of tracheal rings, ranging from 32 to 41 rings (37.42 ± 0.81 rings). A significant reduction in both outer transverse diameter (OTD) and outer vertical diameter (OVD) was observed from the cervical to the thoracic inlet trachea (P<0.007 and P<0.003, respectively). The intraluminal tracheal cross-section shapes observed at the thoracic inlet trachea were horseshoe (50%), crescent (25%), dorsal focal invagination (16.7%), and oval (8.3%) respectively. Surprisingly, a circular shape could not be observed in the thoracic inlet trachea. Additionally, a single straight band with a parallel border throughout the tracheal cartilaginous ring is a typical configuration in all dog’s trachea (93.3%). Conversely, atypical patterns of cartilaginous rings were less observed (6.7%). This study provides valuable novel insights into the anatomical structure and morphological variability of the tracheal ring in dogs.