Cervical Vertebral Instability
Also known as Wobbler’s Syndrome, cervical vertebral instability refers to a compression of the spinal cord in the neck or cervical area. Most commonly, the compression is caused in the Doberman by ventral disc protrusions — instabilities in the spinal cord. The disease is thought to be heritable because it occurs in littermates and families, but overnutrition — overfeeding of protein, calcium and phosphorus that may result in rapid growth and induce skeletal changes — is theorized to be a factor. Onset tends to be slow and progressive. Although CVI may occur in any breed, it’s primarily a disease of large and giant dogs, with the majority of cases seen in Dobermans and Great Danes.
In the Doberman, CVI generally occurs during middle age, about 4 to 6 years of age. Clinical signs vary. “The dog may exhibit pain, have a wobbly gait, carry its neck stiffly or hold it down,” says Amy Kapatkin, D.V.M., assistant professor of surgery at the University of Pennsylvania. “Sometimes they’ll be a little worse in the rear legs than the front legs. In severe cases, they can even become partially paralyzed, where they can’t move or walk at all.”
Diagnosis is made via history, clinical signs, radiography to check on vertebral malformation, and myelography to identify the area and amount of compression. Computed tomography scans may also be used to assess compression to the spinal cord.
Treatment options depend on the severity of the clinical signs. “With some dogs, even the paralyzed ones, if you give them some rest, over time they’ll get back up because the spinal cord compression was not a permanent compression but instead an acute insult to the spinal cord. In dogs where the symptoms are very mild, where they only get a little clumsy periodically or they hurt for a week here and there, we often don’t do anything other than recommending non-steroidal anti-inflammatories for pain relief,” says Kapatkin. In those kinds of cases, restricted activity and crate rest may be required for up to a month. They should never again wear neck leashes, which can put pressure on the neck, but instead wear harnesses when walked. “If the dog is chronically in pain or has neurologic deficits that do not resolve very quickly,” says Kapatkin, “we need to do surgical intervention to decompress, or stabilize, the spinal cord.” This surgical procedure fuses the space between two sections of the spinal cord.
The prognosis for surgical treatment depends on the location and the number of lesions. “The number of lesions is important because if the problem is instability, it is not possible to fuse more than two spaces on the spinal cord,” Kapatkin says. “In those cases, we need to do a large dorsal laminectomy over many spaces, which often clinically helps but is not the most indicated surgery for the presenting lesions.
Each vertebra (segment) on the spinal cord is numbered c1, c2 and so on. Location may be a factor only because it is difficult to repair the space between vertebra c6 and c7, but certainly possible. CVI occurs between c2 and c7 in the Doberman, more commonly between c5 and c7.
“In the Doberman, CVI tends to be a middle-age disease, and sometimes if you fix one spot, there seems to be a domino effect that causes other spots to collapse down the road,” Kapatkin warns. “When the disease occurs in a very young dog, with surgery, these dogs often do well for the rest of their lives. This is because they usually have stenotic spinal canals and early decompression may make them clinically normal. So prognosis is variable, depending on age.” The recovery period ranges from one week to several months.
Dog Breeders may be able to reduce incidences in their lines by selecting away from dogs in which CVI shows up in the family, Kapatkin says. Owners themselves may help prevent the disease, too, by not overfeeding young dogs and causing fast, enormous growth rates. Experts at the University of Illinois recommend a well-balanced diet without supplementing minerals and switching large breed, fast-growing dogs to an adult food at 6 months of age.
Researchers are also studying the disease. Nick Sharp, D.V.M., Ph.D., is investigating the role of CT scans in confirming the diagnosis of CVI and evaluating the dog’s suitability for surgery. The DPFA is helping to underwrite this project.
