Normally, the spinal cord is surrounded and protected by the vertebrae of the spinal column. In spina bifida, there is defective fusion of the vertebral arches during embryonic development, so that the vertebrae are incomplete. The abnormalities range from only nonfusion of a small part of one or a few vertebrae, to most of the vertebral arch being absent on several adjacent vertebrae with protrusion of the spinal cord and/or its lining (meninges) through the defect. In the first case the dog will have no medical problems, but with more severe defects there will be clinical signs associated with the area of the spinal cord that is affected. Spina bifida may occur anywhere in the spinal column but is seen most often in the lower back region (caudal lumbar spine).
Both genetic and environmental factors (toxins, nutritional deficiencies during pregnancy) can produce spina bifida.
The condition is thought to be inherited, but the mode of inheritance has not been identified.
Most often, spina bifida occurs in the lower back region (caudal lumbar spine). The clinical signs vary with the extent of the defect. With a mild defect, you will likely never know there is an abnormality unless your dog has x-rays that show the area.
When the spinal cord itself is affected, you will see signs in the hind end ranging from weakness and incoordination to paralysis and urinary and fecal incontinence. With a severe defect (absence of several adjacent vertebral arches with protrusion of spinal cord), signs are generally evident very early, when pups start to walk.
In severe cases in young pups, your veterinarian may recognize the condition on physical examination. Diagnosis is confirmed by x-ray.
With a mild defect, your veterinarian may find this abnormality incidentally when an x-ray is performed.
There is no effective treatment for dogs with spinal cord malformations. No treatment is necessary for dogs in whom spina bifida is discovered incidentally on radiographs. Reconstructive surgery may be helpful for mildly affected animals.
Absence of the vertebral arch or failure of fusion of dorsal spinous processes in one or more vertebrae may be evident on plain radiographs, and may be seen as an incidental finding. Neurological signs may or may not be present depending on the extent of the defect. Most commonly, spina bifida occurs in the caudal lumbar spine, with clinical signs consistent with a transverse myelopathy from L4 to S3 spinal cord segments.
Although the mode of inheritance has not been established, it is safest not to breed from families where spina bifida has occurred.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
LeCouteur, R.A., Child, G. 1995. Diseases of the spinal cord. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, pp. 629-696. W.B. Saunders Co., Toronto.