Gait evaluation in the pediatric patient can initially be difficult as puppies first learn to walk and the myelination process
matures. As development progresses spinal disorders may become more apparent. Numerous congenital abnormalities resulting
in spinal malformation exist. Spinal malformations most commonly are asymptomatic. However, spinal malformations may lead
to mild or significant dysfunction.
Hemivertebrae are wedge shaped vertebrae, with the base oriented ventrally, dorsally or medially. A hemivertebra occurs when
a portion of the vertebra does not form, typically the vertebral body. Failure of the central portion of the vertebra to form
may result in hemivertebrae on both sides and is called a butterfly vertebra. Hemivertebrae are common in screw tail breeds.
Traumatic and pathologic fractures should be distinguished from hemivertebrae as they can appear similar.1,2 Hemivertebrae
can lead to severe spinal angulation resulting in kyphosis, scoliosis or lordosis.2 Plain radiographs may diagnosis vertebral
anomalies. However, myelography, CT or MR imaging are required to assess the degree of spinal cord compression. Non steroidal
anti-inflammatory (NSAID) therapy may be of benefit if pain or mild paresis is present. If NSAID therapy is unsuccessful or
if paresis is severe then prednisone therapy at anti-inflammatory dosages (0.5 mg/kg PO BID initially and then tapered) may
be successful. If paresis is severe or if progressive despite medical therapy, then surgical decompression ± stabilization
is recommended. The prognosis with surgery may be guarded due to concurrent spinal malformations,2 and chronicity.1
Block vertebrae result from embryonic failure of segmentation. Block vertebrae are typically shorter than the sum of the individual
segments. Differential diagnoses for block vertebrae include vertebral fusion following a previous fracture, discospondylitis
or previous disk surgery.1,2
Transitional vertebrae occur at the junction of the divisions of the vertebral column. The thoracolumbar junction is commonly
affected, with unilateral or bilateral defects. The thirteenth thoracic vertebra may have a short thick transverse process
instead of a rib. Less commonly, the first lumbar vertebrae may have a rib instead of a transverse process.1 Transitional
vertebrae at the thoracolumbar junction do not appear to cause a significant clinical problem. However, the last rib is commonly
used for localization during the surgical approach for hemilaminectomy. Thus, a malformation at this location could lead to
an inappropriate surgical location. Identification of thoracolumbar vertebrae is more difficult via MR imaging. With the increasing
availability and use of MR imaging this should be considered.