Radiographic tracheal comparison among American, English, and French bulldogs via the utilization of manubrium and thoracic inlet tracheal indices.

Tracheal hypoplasia is a congenital abnormality associated with brachycephalic airway syndrome, resulting in a generalized decrease in tracheal lumen diameter (TLD). Radiographic techniques to assess tracheal narrowing have been described; however, comparisons of tracheal diameter among breeds of bulldogs have not been made. The objective of this study was to investigate potential differences in standardized tracheal lumen diameters among bulldog breeds at different regions of the trachea and determine whether breed-specific reference values should be established. Medical records and thoracic radiographs were reviewed for clinically asymptomatic American, English, and French bulldogs. TLDs at three defined, well-established regions (caudal cervical, thoracic inlet, and intrathoracic trachea) were measured and standardized using manubrium length (ML) and thoracic inlet distance (Ti-D). One hundred dogs met the inclusion criteria and were represented by 33 American bulldogs, 33 English bulldogs, and 34 French bulldogs. No significant difference was found in the average manubrium tracheal index (M-TI) among bulldog breeds. A significant difference was found (p < 0.001) in the average thoracic inlet tracheal index (Ti-TI) among breeds, with the difference attributed to American bulldogs versus French and English bulldogs. This discrepancy might be attributed to the thoracic vertebral anomaly (TVA) associated with bulldogs. MT-I may be a reliable alternative to Ti-TI due to the potential influence of TVA on Ti-D.