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Hemivertebrae in Dogs

 

Hemivertebrae in dogs is a genetically inherited bone malformation affecting the vertebrae of the dog’s spine. The term inherited in this case implies that if a dog has the condition, the majority of the time, its parents either actively had the condition or passed along the gene silently (recessive inheritance). Dogs with hemivertebrae typically have wedge- shaped vertebrae that appear as butterfly wings spread open when viewed from the top. Hemivertebrae in dogs are a serious issue because they can cause neurological conditions, and this happens when the affected area has pressure applied to it.

Pug are prone to hemivertrabrae

Symptoms of Hemivertebrae in Dogs

The physical symptoms for this condition may vary on an individual basis. In some cases, dogs may develop no symptoms at all, and therefore they are labeled as being asymptomatic despite having this malformation. Generally, though, affected dogs show several signs and symptoms.

On x-rays, the back spine is malformed in such a way that is hunched, twisted to the side, or curves inward. Misshapen vertebrae like wedges, which cause the back to curve unnaturally, may be noticed as well.

It is important to distinguish hemivertebrae from traumatic and pathologic fractures which may be confused one for another.

The onset and degree of symptoms developing in affected dogs varies and depends on what part of the spinal column is affected and whether there is compression of the spinal cord. Most severe symptoms are present when a vertebrae is so deformed to the point of causing pressure on the spinal cord.

Symptom-wise, owners may witness neurological issues such as rear leg weakness, muscle atrophy, paralysis, incontinence and incoordination. Affected dogs may also display back pain, including inability to get up or lie down or the dog not being able to properly attend to his rear end grooming.




 Breeds Mostly Affected by Hemivertebrae

The dogs most affected by this genetic condition are breeds with shorter skulls, as well as screw-tailed or curly-tailed dog breeds. Generally pugs, Boston terriers, English and French Bulldogs are affected. When limited to the tail area, in many cases it doesn’t cause serious problems.

 The breeds that are most commonly seen with hemivertebrae in other areas of the spine include German Short Haired Pointers and German Shepherds. In such breeds the hemivertebrae affect the middle of the back leading to roaching or arching of the back, painful and unstable, weakened areas (“weak links”) which may be prone to injuries later on in life. According to the Canine Inherited Disorders Database, in these breeds, the condition is autosomal recessive.

In other dog breeds, the mode of inheritance remains unknown. The condition is for a good extent seen in dogs who have a parent in their family tree who have it. Due to the genetic component of this malformation, it’s imperative to point out the importance of careful breeding and removal from breeding programs of specimens affected.

However, there are cases where the breed is not at risk and no parents have the condition, but the pup still has hemivertebrae.

At the Vet’s Office

Hemivertebrae in dogs is most commonly found in the top of the dog’s back: the length of spine that is in front of his shoulders / bottom of his neck to where the bottom of his rib cage would be seen below.

A quick test that the vet may perform is to press gently in this area – but enough to apply pressure – and observe the dog’s reaction. This is because hemivertebrae typically cause neurological symptoms when there is pressure in the area, including compression in the spine. Most veterinarians will likely order a few tests to be sure of the diagnosis.

A positive diagnosis of hemivertebrae is usually aided with an x-ray, x-ray with dye indicator, CT, or MRI, though the most common of these is the x-ray with dye indicator, called a myelography. Only myelography, CT or MR imaging are capable of assessing the degree of spinal cord compression.

Typically the birth defect is not apparent until the dog is 4 to 10 months old, when rapid bone growth takes place. But it may manifest during fetal development, while still in the mother’s womb; this typically results in a still-birth pup, or a pup who dies soon after birth, especially in  English bulldogs.

 Treatment of Hemivertebrae in Dogs

Not all dogs who have hemivertebrae need treatment; some dogs are able to coexist with their deformity and still lead happy, pain-free lives. For example, recently experts have agreed that the kink in curly-tailed dogs is actually caused by hemivertebrae. For most dogs where hemivertebrae has manifested in the dog’s tail, the dog does not need any medical intervention – it is only when the hemivertebrae affects the spine that serious issues follow.




Most cases of hemivertebrae in dogs are quite treatable. For dogs with only light or mild hemivertebrae will find an easy conservative treatment option of non steroidal anti-inflammatory (NSAID) drugs,  restriction from activity and possibly a diet review to try to give the dog the most anti-inflammatory foods possible. When NSAID use is not successful, prednisone therapy given at an anti-inflammatory dosage can be helpful.

For dogs with moderate to severe cases, recent advances in medicine and understanding of the disease has enabled treatment via surgery on the spine, either to stabilize the spine, decompress it, or both. Special precaution with anesthesia for the surgery is taken in dog breeds who are at risk for hemivertebrae as several breeds are also known for compromised breathing. For dogs with the most severe cases of hemivertebrae, euthanasia may be the most ethical choice.

Alternative treatment options for hemivertebrae are also being studied. One study found that acupuncture and Chinese herbs could help single leg paralysis, as well as the pain from hemivertebrae, but wouldn’t help dogs suffering from incontinence.

Preventing Hemivertebrae in Dogs

Because these malformations are genetically inherited, there are ways to prevent the disorder from being passed on to future litters. A general health screening as well as x-rays of the sire and dam will help prevent the traits from being passed on in questionable.

Knowing the health history of the lineage of both parents is also important, as the trait can be passed down by recessive inheritance – where the gene is passed onwards without being activated.

If hemivertebrae is present in the sire or dam in non-problematic areas (the tail), it is recommended not to breed as the probability of hemivertebrae being passed on is strong, and hemivertebrae doesn’t always stay confined to a single area when passed on.

Beyond this, watching the pregnant dog to make sure that she is well fed, doesn’t have much stress, and doesn’t have any nutritional deficiencies are the general path towards overall wellness. The owner can also take precautions to keep away chemicals and toxins that are known to cause birth defects, as hemivertebrae can start to develop even while a puppy is still in the fetus stage, caused by not enough blood flow to the hindquarters and tail area.


References

  • Irish Veterinary Journal, 2005; 58(12): 688–690 Nasca classification of hemivertebra in five dogs, Omer Besalti et al.
  • Journal of Traditional and Complementary Medicine.Acupuncture combined with Chinese herbs for the treatment in hemivertebral French bulldogs with emergent paraparesis, Ching Ming Liu, G. Reed Holyoak, and Chung Tien Lin, 2016 Oct; 6(4): 409–412. Published online 2015 Dec 11
  • Morgan J.P. Congenital anomalies of the vertebral column of the dog: a study of the incidence and significance based on a radiographic and morphologic study. J Am Vet Radiol Soc. 1968;9:21–29.
  • Bailey CS, Morgan JP. 1992. Congenital spinal malformations. Veterinary Clinics of North America Small Animal Practice. 22(4):985-1015.

 

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