Which vertebral condition involves an osseous fusion between two or more adjacent vertebrae and is often asymptomatic?

Which vertebral condition involves an osseous fusion between two or more adjacent vertebrae and is often asymptomatic?

• A. Block vertebra
• B. Spina Bifida
• C. Dermoid Sinus
• D. Hemivertebra

Answer: (A)

Block vertebra is a congenital fusion of two or more adjacent vertebrae, where the normal segmentation process fails and the bones fuse together. This creates a single, immobile segment and is often discovered incidentally on radiographs because many animals show few or no clinical signs. The key imaging clue is a continuous bony bridge between vertebral bodies and the loss of the normal intervertebral disc space at the fused level. Spina bifida, by contrast, is a neural arch closure defect rather than a fusion of vertebral bodies. Dermoid sinus is a skin–to–deep-tissue tract and not a vertebral body fusion. A hemivertebra results from incomplete formation of a vertebral half, producing wedge-shaped vertebrae and typically causing curvature, not a fused block.

Block vertebra is a congenital fusion of two or more adjacent vertebrae, where the normal segmentation process fails and the bones fuse together. This creates a single, immobile segment and is often discovered incidentally on radiographs because many animals show few or no clinical signs. The key imaging clue is a continuous bony bridge between vertebral bodies and the loss of the normal intervertebral disc space at the fused level.

Spina bifida, by contrast, is a neural arch closure defect rather than a fusion of vertebral bodies. Dermoid sinus is a skin–to–deep-tissue tract and not a vertebral body fusion. A hemivertebra results from incomplete formation of a vertebral half, producing wedge-shaped vertebrae and typically causing curvature, not a fused block.