Hemivertebrae in Dogs - Congenital Spinal Malformation

Hemivertebrae in Dogs - Congenital Spinal Malformation

Important note: Fidello is not a veterinarian. This page is meant to inform you and does not provide a diagnosis. If you're unsure about your dog's health, or recognise the signs described below, always contact a veterinarian.

Hemivertebrae is the veterinary term for one or more vertebrae that did not develop normally before birth. Instead of the usual, roughly block-shaped vertebra, a wedge- or butterfly-shaped vertebra forms, which can affect the shape of the spine. In some dog breeds this is remarkably common, usually without the dog ever noticing anything.

What is hemivertebrae?

During embryonic development, each vertebra normally grows from two halves that fuse together. In hemivertebrae, this formation is incomplete, so a vertebra takes on an abnormal, wedge- or butterfly-shaped form instead of the usual shape. One or more vertebrae can be affected, most often in the chest (thoracic) section of the spine. Because the affected vertebra is not symmetrical, the spine can become slightly twisted or curved at that point (kyphosis or scoliosis). In many dogs this causes no consequences at all; in some dogs, however, the abnormal shape does press on the spinal cord.

Which dogs are at risk?

Hemivertebrae is reported particularly in screw-tailed and brachycephalic breeds, such as the French Bulldog, the Pug and the English Bulldog. In French Bulldogs, imaging studies often find at least one hemivertebra in a large proportion of dogs, frequently without this ever causing symptoms. In Pugs the malformation occurs somewhat less often, but the chance of it actually causing symptoms appears relatively higher. Research points to a hereditary component: the predisposition for the number and severity of hemivertebrae can be passed from parent dogs to offspring. An inherited form has also been described in other breeds, including the German Shorthaired Pointer. A hereditary predisposition does not automatically mean a dog will ever develop symptoms.

Symptoms

Most dogs with hemivertebrae never show symptoms; the malformation is then found incidentally on an X-ray taken for another reason. When symptoms do occur, this usually happens at a young age, because pressure on the spinal cord can increase during the growth phase. Early signs may include: a slightly wobbly or unsteady hindquarters, more difficulty getting up, or a noticeably altered posture of the back. Signs that require urgent attention include: sudden weakness or paralysis of the hind legs, clear pain, or the inability to hold urine or stool.

When to see a vet?

Contact a veterinarian if you notice an abnormal back posture, if your dog seems unsteady or weak in the hindquarters, or if a previous examination has already shown a hemivertebra and you are unsure whether a check-up is needed. In the case of sudden paralysis, obvious pain, or an inability to hold urine or stool, an urgent appointment is needed: this can indicate increasing pressure on the spinal cord.

How is it diagnosed?

A veterinarian can often already see an abnormal vertebral shape on plain X-rays. To assess whether the malformation is actually pressing on the spinal cord, more advanced imaging is needed, such as a CT or MRI scan, sometimes combined with a myelogram. This page cannot determine whether your dog has hemivertebrae, or to what degree; only a veterinarian can assess that after examination.

Treatment in outline

In dogs without symptoms, no treatment is often needed, though regular check-ups are still advisable. For mild symptoms, a veterinarian may choose rest, restricted exercise and, where appropriate, pain- or anti-inflammatory medication. For severe or worsening pressure on the spinal cord, surgery may be considered, in which the pressure is surgically relieved and the spine is stabilised where needed. Which approach is appropriate depends on the severity of the malformation, the dog's age and the exact location, and is always determined by the veterinarian.

What you can do yourself

Prevent a dog with hemivertebrae from becoming overweight, since extra weight puts additional strain on the back. Avoid forceful jumping (for example off the sofa or out of the car) and prolonged, strenuous exercise, especially in young, still-growing dogs. A firm, well-supporting resting place, together with calm, regular movement rather than short bursts of intense activity, can contribute to everyday comfort. This does not replace veterinary guidance.

Prevention and responsible breeding

Because hemivertebrae has a hereditary component, responsible breeding forms an important part of prevention. In breeds with an increased risk, it is recommended that breeding dogs are screened beforehand for, among other things, back and vertebral abnormalities, and that dogs with many or severely affected vertebrae are not bred from, especially in combination with other health issues. As a buyer of a puppy from an at-risk breed, ask the breeder for these results.

Living with hemivertebrae

Most dogs found to have hemivertebrae lead a completely normal life without noticeable limitations. In dogs that do develop symptoms, veterinarians often see the situation stabilise once the spine has finished growing, usually around nine months of age. With the right guidance, an adapted activity pattern and regular check-ups, dogs with a more pronounced form can generally still have a good quality of life.

Frequently asked questions

Is hemivertebrae always visible from the outside?
No, in many dogs the back looks entirely normal, and the malformation is only visible on X-rays.

Does hemivertebrae mean my dog will never walk normally?
No, most dogs with hemivertebrae never develop symptoms; severity and consequences vary considerably from dog to dog.

Is surgery always necessary?
No, surgery is only considered in dogs with demonstrable, problematic pressure on the spinal cord; the veterinarian assesses this on a case-by-case basis.

Can I prevent hemivertebrae in my dog?
Not entirely, since there is a hereditary component; responsible breeding can, however, reduce the risk.

Conclusion

Hemivertebrae is a congenital vertebral malformation that occurs mainly in brachycephalic and screw-tailed breeds, and that remains without consequences in most dogs. In some dogs, however, the abnormal vertebral shape can press on the spinal cord, with symptoms usually appearing at a young age. Contacting a veterinarian promptly for an abnormal back posture or hindquarter symptoms, together with responsible breeding in at-risk breeds, makes the difference between a dog with unnecessary symptoms and a dog that notices very little of it throughout its life.

In closing

In closing: this article does not replace a visit to the vet. Fidello does not provide diagnoses or prescribe treatments. If in doubt, or if symptoms persist or appear urgent, a veterinarian is always the right next step.