Degenerative diseases

By | July 22, 2013

Intervertebral disc disease

Spinal cord compression secondary to intervertebral disc protrusion or extrusion is one of the most common clinical neurological disorders. Protrusion describes a disc that is ‘bulging’ into the vertebral canal, whereas extrusion describes a situation where the central nuclear material of the disc has ruptured through the dorsal fibrous structures into the vertebral canal. Acute (type I) cervical disc herniations commonly cause pain, which may be manifested as a ‘nerve root signature’, without obvious neurological deficits; the severity of the pain may be such that surgery is required. The pathophysiology, diagnosis and treatment of disc disease are discussed in site.

Cervical stenotic myelopathy (Wobbler syndrome)

Also termed caudal cervical spondylomyelopathy, cervical spondylopathy, cervical spondylolisthesis, cervical malformation / malarticulation and disc-associated wobbler disease, this disorder most commonly affects Dobermann Pinschers and Great Danes, but many other breeds have been recognized with similar abnormalities. The age of onset of the disease is variable, ranging from 3 months to 9 years. Neck pain may be the only clinical sign of the disease; however, pelvic limb ataxia, pelvic limb paresis and ambulatory tetraparesis are commonly associated with the discomfort. For a complete discussion of the pathophysiology, diagnosis and treatment of this disease, the reader is directed to site.

Spinal synovial cysts

Extradural spinal synovial cysts originating from articular facet joint capsules that cause compression of the spinal cord have recently been described in dogs, and occur most commonly in the cervical vertebrae (). Further information can be found in site.

Spondylosis deformans

Spondylosis deformans is a degenerative, non-inflammatory, proliferative disease of the vertebral column characterized by the presence of vertebral osteophytes at intervertebral disc spaces, resulting in the formation of spurs or complete bony bridges.

Clinical signs: The condition is usually subclinical, although stiffness, restricted motion, and pain might be attributed to spondylosis deformans in a small percentage of patients. All other causes of neck pain should be ruled out before spondylosis is definitively associated with the signs.

Pathogenosis: This disease has been reported in dogs from 2 years of age, with 75% of dogs with spondylosis deformans affected to some extent by 9 years of age (). It has been reported with high incidence in Boxers, in which it may be an inherited condition. In this breed, it is more commonly seen in females; it can involve the whole spine, although it is more often found in the thoracolumbar spine than in the cervical spine. Trauma, degenerative disc disease and intervertebral discfenestration have all been associated with the formation of spondylosis deformans; however, it may occur in the absence of these three. Osteophytic projections into the spinal canal causing compression of the spinal cord are rare, as is osteophytic compression of spinal nerves at the level of the intervertebral foramina, although it has been reported at the lumbrosacral (LS) junction ().

Diagnosis: Diagnosis is based upon ventrodorsal, lateral () and oblique spinal radiography, but demonstrating soft tissue and neural tissue involvement requires advanced imaging such as MRI ().

Treatment and prognosis: Treatment relies on analgesia, if required, and, possibly, surgical decompression, but this is rarely needed. If spondylosis is causing clinical signs, the prognosis may be guarded, due to the high probability of recurrence and / or progression.

Dural ossification

Dural ossification is a degenerative condition of dogs of unknown aetiology, characterized by deposition of bone plaques on the inner surface of the dura mater. These plaques occur most commonly in the cervical and lumbar regions of the spine and are common incidental findings on radiographic studies of the spine; although clinical disease has been documented, due to associated spinal cord compression (), this should primarily be regarded as an incidental finding.

Calcinosis circumscripta

Sometimes called tumoral calcinosis, calcinosis circumscripta (CC) has been reported to cause spinal cord compression in several breeds of dog (Bernese Mountain Dogs, German Shepherd Dogs, English Springer Spaniels, Rottweilers and Great Danes) less than a year old; compressive disease is usually localized dorsally at the atlantoaxial articulation ().