Overview
The dog has seven lumbar vertebrae, with longer and sturdier bodies than the thoracic ones. L1 follows the last thoracic vertebra (T13) and no longer has costal foveae. Its transverse processes are long, flat and point cranially and ventrally, increasing in length up to L5 or L6.
Key features
- Body: long, with a slightly keeled ventral surface.
- Spinous process: wide, tilted cranially (from the anticlinal vertebra T11 onward the spinous processes point cranially).
- Articular processes: the cranial ones face medially and the caudal ones laterally, interlocking in a sagittal plane that allows flexion and extension but almost no rotation.
- Mammillary and accessory processes: the mammillary processes sit on the cranial articular processes; the accessory processes are small caudal projections.
- Vertebral canal: contains the last thoracic and first lumbar segments of the spinal cord.
Clinical relevance
The thoracolumbar junction (T11-L3) hosts most disc herniations (Hansen type I intervertebral disc disease) in chondrodystrophic breeds such as the Dachshund, with acute-onset paraparesis or paraplegia. It is also a frequent site of traumatic vertebral fractures and luxations. The lumbar spinous processes are landmarks for lumbar puncture (L5-L6 in the dog).