There are also coronal clefts mainly in skeletal dysplasias such as chondrodysplasia punctata. In dogs, butterfly vertebrae occur most often in Bulldogs, Pugs, and Boston Terriers. Transitional vertebrae
Transitional vertebrae have the characteristics of two types of vertebra. 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 vertebra may resemble a rib. A transitional vertebra at the lumbosacral junction can cause arthritis, disk changes, or thecal sac compression. Back pain associated with lumbosacral transitional vertebrae (LSTV) is known as Bertolottis syndrome. 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.The significance of transitional vertebrae has been questioned by one study finding similar prevalence in the general population as those with low back pain,  but more recent study found a large difference. 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.
In sacralization, the L5-S1 intervertebral disc may be thin and narrow. This abnormality is found by X-ray.Sacralization of L6 means L6 attaches to S1 via a rudimentary joint. This L6-S1 joint creates additional motion, increasing the potential for motion-related stress and lower back pain/conditions. This condition can usually be treated without surgery, injecting steroid medication at the pseudoarticulation instead. Additionally, if L6 fuses to another vertebra this is increasingly likely to cause lower back pain. The presence of a sixth vertebra in the space where five vertebrae normally reside also decreases the flexibility of the spine and increases the likelihood of injury. Hemivertebrae
Hemivertebrae are wedge-shaped vertebrae and therefore can cause an angle in the spine (such as kyphosis, scoliosis, and lordosis). Among the congenital vertebral anomalies, hemivertebrae are the most likely to cause neurologic problems. 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, urinary 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. Associations
Recognised associations are many and include:
Aicardi syndrome,
cleidocranial dysostosis,
gastroschisis 3,
Gorlin syndrome,
fetal pyelectasis 3,
Jarcho-Levin syndrome,
OEIS complex,
VACTERL association.The probable cause of hemivertebrae is a lack of blood supply causing part of the vertebrae not to form.