Overview

Hemivertebrae is a congenital spinal abnomality, in which the vertebrae fail to develop into a normal, symmetrical shape, resulting in an angle in the spine. This abnormal development occurs in the womb, and inadequate blood supply is suspected to be a probable cause. In dogs, several breeds are more predisposed to have this condition, including the English Bulldog, French Bulldog, Pug, and Boston Terrier. Most frequently this condition occurs in the tail, which causes a bent known as a “screw tail.” Screw tails are common traits in these breeds and are oftentimes a desirable characteristic which breeders might actively select. The special shape of the tail has no influence on the dog’s normal function, and is a purely cosmetic trait. However, when hemivertebrae occur in other parts of the spine it becomes a potentially serious condition, which can cause physical deformities and neurological problems.

This condition does have a genetic component, since certain breeds are more likely to have it. Other than the screw-tailed breeds, it has also been shown that German Shorthaired Pointers and Yorkshire Terriers can also inherit this condition.

Symptoms and Diagnosis

Depending on the degree of deformity, the deviation of the spine may be small and not immediately apparent. If the vertebral column is twisted so that the spinal cord becomes compressed, the dog will display neurological symptoms which include weak rear limbs and incontinence. An X-ray of the spine can usually confirm the presence of deformed vertebrae, while more advanced imaging (such as MRI or CT) might be needed to see if the spinal cord is being compressed by the bones.

Treatment

In mild cases when the spinal cord is not affected and the dog is otherwise healthy, no treatment is necessary. In fact, sometimes the slight deformity is only discovered when an X-ray is done to examine other problems. In cases where spinal cord compression occurs and causes neurological issues, different treatments are available depending on the severity of the compression. If the spinal cord is only periodically pressurized and irritated, an injection of corticosteroid to relieve the inflammation might be sufficient. More severe compression will require surgical correction. Specific treatment regimes will depend on the location and characteristic of the deformity.