Issue Description Congenital vertebral anomalies are a
collection of malformations of the spine in animals. Most are not
clinically significant, but they can cause compression of the spinal
cord by deforming the vertebral canal or causing instability. This
condition occurs in the womb. Congenital vertebral anomalies include
alterations of the shape and number of vertebrae.
Hemivertebrae Among the congenital vertebral anomalies,
hemivertebrae are the most likely to cause neurologic problems. They
are wedge shaped vertebrae, and therefore can cause an angle in the
spine (such as kyphosis, scoliosis, and lordosis). The most common
location is the midthoracic vertebrae, especially the eighth (T8).
Neurologic signs result from severe angulation of the spine, narrowing
of the spinal canal, instability of the spine, and luxation or
fracture of the vertebrae. Signs include rear limb weakness or
paralysis, urine or fecal incontinence, and spinal pain. Most cases of
hemivertebrae have no or mild symptoms, so treatment is usually
conservative. Severe cases may respond to surgical spinal cord
decompression and vertebral stabilization.
cause of hemivertebrae is a lack of blood supply causing part of the
vertebrae to not form. Hemivertebrae in dogs are most common in the
tail, resulting in a screw shape, but can also occur in the thoracic
vertebrae. Affected dog breeds include Bulldogs and French Bulldogs,
Pugs, and Boston Terriers. It is inherited in Yorkshire Terriers and
German Shorthaired Pointers. The condition can cause death in very
young Bulldog puppies.
Block Vertebrae Block vertebrae occur when there is improper
segmentation of the vertebrae, leading to parts of or the entire
vertebrae being fused. It can lead to an angle in the spine, but there
are usually no symptoms. The sacrum is a normal block vertebrae.
Butterfly Vertebrae Butterfly vertebrae have a cleft through the
body of the vertebrae and a funnel shape at the ends. This gives the
appearance of a butterfly on an x-ray. It is caused by persistence of
the notochord (which usually only remains as the center of the
intervertebral disc) during vertebrae formation. There are usually no
symptoms. Butterfly vertebrae occur most often in Bulldogs, Pugs, and
Transitional Vertebrae Transitional vertebrae have the characteristics
of two types of vertebrae. The condition usually involves the
vertebral arch or transverse processes. It occurs at the
cervicothoracic, thoracolumbar, or lumbosacral junction. For instance,
the transverse process of the last cervical vertebrae may resemble a
rib. A transitional vertebrae at the lumbosacral junction can cause
arthritis, disk changes, or spinal cord compression. One study found
that male German Shepherd Dogs with a lumbosacral transitional
vertebra are at greater risk for cauda equina syndrome, which can
cause rear limb weakness and incontinence.
Spina Bifida Spina bifida is characterized by a midline
cleft in the vertebral arch. It usually causes no symptoms in dogs. It
is seen most commonly in Bulldogs and Manx cats. In Manx it
accompanies a condition known as sacrocaudal dysgenesis that gives
these cats their characteristic tailless or stumpy tail appearance. It
is inherited in Manx as an autosomal dominant trait.