Congenital Defects
Of the Vertebral Column in Dogs

Cervical vertebral instability is commonly known as canine wobbler syndrome.  Several other terms have however also been used to describe this disease, including caudal cervical malformation-malarticulation, cervical spondylopathy and cervical vertebral stenosis.  The term "wobbler" is non-specific and it simply describes a dog with generalized ataxia (loss of the power of governing movements) and tetraparesis (muscular weakness affection all four limbs) that may be attributed to a number of different conditions of the cervical (neck) spinal cord.

Cervical vertebral instability commonly occurs in young grown Great Danes (less than 2 years of age), adult Rottweilers and adult Doberman Pinschers (5 - 8 years of age) and other large dog breeds.  Other dog breeds in which cercival vertebral instalibility has been reported include the Saint Bernard, Weimaraner, Labrador retriever, German shepherd, Boxer, Basset hound, Rhodesian ridgeback, Dalmation, Samoyed, Old English sheepdog, and Bull mastiff.  Male dogs are more commonly affected.

The high incidence of cervical vertebral instability in certain dog breeds suggest that heredity is a contributing factor.  this can be supported by the finding that the breeding of affected individuals resulted in high incidence of cervical vertebral instability in the progeny.  Over-nutrition and rapid growth have also been implicated as contributing factors.  Trauma has however been ruled out in the majority of reported cases.  Clinical signs result from spinal cord compression, malformations, malarticulations or combinations thereof.

Clinical signs are most often progressive in nature and the signs gradually worsen over several months or years.  Initially gait deficits are frequently noted in the hind (pelvic) limbs.  This mild hind limb ataxia progresses in severity resulting in a wide-based, crouching stance as well as dragging or knuckling of the toes of the hind limbs.  These abnormalities may be more pronounced when the affected og rises from a lying down position or turns.  During walking, but especially during turning, the hind limbs often cross each other and with the stride often being longer than normal and asymmetric, a typical awkward swaying movement of the hindquarters may be visible.  Hypertonia (increased tightness of muscle tone) as well as hyperreflexia (exaggeration of reflexes) can also be seen in the hind limbs.  Abnormalities in the font limbs often only occur after the development of hind limb abnormalities and these deficits are usually milder in severity.  Although these signs are due to neck involvement, manipulation of the cervical area does not elicit pain.

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Cervical vertebral instability can be most accurately diagnosed by means of radiographs and myelograms (specialised X-ray of spinal cord following injection of a contrast medium).  It is important that cervical vertebral instability be differentiated from other possible causes of similar signs, such as vertebral fractures, intervertebral disc prolapse, and space occupying lesions causing spinal cord compression (e.g. cancerous growths, and abscesses).

Treatment of cervical vertebral instability either focuses on the relief of clinical signs by means of medical treatment and management practices or surgical relief of spinal cord compression, stabilization of vertebrae or both.  Medical therapy involves the use of anti-inflammatory drugs and management procedures that reduce neck movement, such as close confinement.  Medical therapy does however not alter sustained and often progressive spinal cord compression and may only provide clinical improvement for a variable period of time.

It is often difficult to determine a prognosis for a dog with cervical vertebral instability.  The prognosis for dogs with cervical vertebral instability that has a chronic history of worsening signs is not as favourable as for dogs with acute (sudden) onset of signs.  Mildly affected dogs have a fair prognosis for recovery.  Dogs with a single spinal cord compression appear to have a better prognosis than dogs with multiple spinal cord compressions.