Computed tomographic assessment of congenital bone fusions in the thoracic vertebral column in 51 French bulldogs

Congenital vertebral malformations are frequently identified on computed tomographic examinations in French bulldogs. However, little information is available regarding congenital bone fusion in the thoracic vertebral column in this breed. The primary aim of this study was to characterize the types and determine the prevalence of congenital bone fusion affecting the thoracic vertebral column in French bulldogs. The secondary aim was to identify the thoracic vertebral malformations most commonly observed with congenital bone fusion and to evaluate the presence of kyphosis and scoliosis. Computed tomographic scans of 51 dogs with congenital bone fusion in the thoracic vertebral column were evaluated. These scans revealed failure of vertebra formation in 18 dogs (35.3%) (partially segmented hemivertebra in 14 dogs, non-segmented hemivertebra in 4 dogs), congenital fused dorsal spinous processes in 38 dogs (74.5%), and costo-vertebral synostosis in 9 dogs (17.6%). Partially segmented hemivertebrae were most commonly observed at the T11–T12 vertebral segment (42.9% of affected dogs), followed by the T10–T11 vertebral segment (28.6%). Non-segmented hemivertebrae consistently resulted in fusion of 3 vertebrae between T10 and L1. Congenital fused dorsal spinous processes were most commonly identified at the T8–T9 vertebral segment (47.3% of affected dogs), followed by the T7–T8 vertebral segment (34.2%). Notably, 12 of the dogs exhibited multiple congenital bone fusion types in their thoracic vertebral column, with fused dorsal spinous processes present in 11 cases. The most common vertebral malformations occurring within the congenital bone fusion were ventral and median aplasia of the vertebral body (39.2%), ventral and median hypoplasia of the vertebral body (37.2%), and short vertebra (35.3%). Kyphosis was diagnosed in 12 dogs, whereas scoliosis in 1 dog. Congenital bone fusion in the thoracic vertebral column occurred in various forms and predominantly affected the middle and caudal thoracic vertebrae. Kyphosis and scoliosis were frequently identified in dogs with congenital bone fusion of the thoracic vertebrae. A further study is necessary to assess the clinical significance of different types of bone fusions in the thoracic vertebral column in French bulldogs.