There are several diseases that may involve the spinal canal producing clinical signs
including neurological deficits and these need to be differRadiography is important
in reaching an accurate diagnosis and myelography is usually needed to identify space
occupying lesions. Aniwith gait abnormalities should also have non-neurological causes
eliminated including osteoarthritis (or degenerative joint disease), hip dysplasia,
bilateral osteochondritis dessicans and generalised bone dise.g. renal secondary
Discospondylitis may occur at any age and occurs most frequently in the cervical
spine or at the lumbosacral junction. It is an inflammatory process (usually secondary
to bacterial infection) of the intervertebral disc space which extends into the vertebral
bodies either side and encroaches on the spinal canal. The diagnosis is confirmed
by radiology and it needs to be differentiated from spondylosis which is a common
incidental radiofinding in older dogs.
Cervical spondylopathy usually occurs in an earlier age (up to 7 years in Dobermans).
Degenerative disc disease
Degenerative disc disease is common in young chondrodystrophic dogs and clinical
signs associated with disc degeneration are unusual in geriatric patients of these
breeds. In other large breed dogs the condition is more likely to be seen in middle-aged
or older animals and they usually present with a gradually progressive hindleg ataxia
and paresis. Anti-inflammatory drugs are the treatment oT choice, and surgery is
less likely to be successful in these patients than in young animals with acute disc
prolapse. Somethere is a concurrent degenerative myelopathy.
Chronic degenerative radiculomyopathy
Most central and peripheral myopathies occur in young animals, but chronic degenerative
radiculomyelopathy (CDRM) is frequenfly seen in elderly male German shepherd dogs
and it is occasionally seen in other breeds. There is degeneration of the lumbar
dorsal columns, fasciculus gracilis, lateral corticospinal tract and around the ventromedian
fissure of the white matter of the cord. Lesions also involve the dorsal spinal roots
and the thoracolumbar grey matter and nucleus gracilis show asytrocytic sclerosis.
These degenerative changes are typical of a 'dying-back' disease (Griffiths and Duncan
The cause is unknown although vitamin B12 (cobalamin) deficiency has been suggested
by some workers.
Diagnosis is based upon the presenting clinical signs (Table 3.10) and absence of
a space occupying spinal lesion on myelography. Treatment is symptomatic, for example
the provision of boots to protect the dorsa of the feet and there is no treatment
that can reverse the neurological deficit.
There are a number of pathological changes that may occur at the lumjunction leading
to signs of low back pain or hyperaesthesia with decreased ability to exercise, difficulty
in rising, and sometimes faecal or urinary incontinence. The signs are usually bilateral
and weak hock flexion is the main neurological deficit (Denny et
al. 1982). Large breed working dogs are most often affected though a similar condition
has been reported in smaller toy breeds.
The aetiopathogenesis may be due to spinal stenosis, disc protrusion, spondylosis
deformans or discospondylitis. Myelography, epidurography, transosseus venography
or CT scan are useful for differentiating the cause and electrophysiological testing
(EMG) is also helpful.
Decompressive surgical treatment (dorsal laminectomy or foris reported to provide
good success, and antibiotic treatment is required for discospondylitis.