Intervertebral disc disease and spinal disorders 

(Clare Rusbridge 2018 ©)

 Intervertebral disc disease is the most common spinal disease in dogs and is increasingly recognised in cats. The intervertebral discs (IVD) are fibrocartilaginous cushions between the vertebrae (except the first 2 cervical vertebrae) that allow movement, are supportive and act as shock absorbers. They consist of a fibrous outer rim, the anulus fibrosis, and a jelly like centre, the nucleus pulposus. IVD degeneration results in diminished shock-absorbing capacity, and can ultimately lead to IVD herniation and spinal cord compression. The types of IVD herniation are often described as Hansen type I (nucleus pulposus degeneration and extrusion) and Hansen type II (anulus fibrosis degeneration and protrusion).

Chondrodystrophic dogs (characteristically have disproportionably short limbs) for example the Bassett Hound, Dachshund, Lucas terriers, Sealyhams and Shih Tzus are predisposed to intervertebral disc disease

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What are the clinical signs of disc disease?
The most common sign is pain localised to the back or neck. Apart from yelping, common signs of spinal pain are abnormal posture (e.g. hunched back with head down), shivering, panting, unwillingness to move and difficulty jumping / doing stairs. In more severe cases there may be difficulty walking – ranging from poor control of the hindlimbs to complete paralysis. Most severe cases have a paralysed bladder and may be unable to urinate and / or dribble urine. The most severe cases are paralysed, have lost bladder function and have lost the ability to feel painful sensations.

How is disc disease diagnosed?

Disc disease may be strongly suspected on the basis of clinical signs especially in predisposed breeds however diagnostic imaging is required to confrim the diagnosis. Spinal radiographs (x-rays) may reveal characteristic changes of disc disease e.g. calcified disc material within the vertebral canal or narrowing of the IVD space or the foramen however radiographs rarely provide the accurate conformation and localisation required for surgical management. In some cases myelography is recommended. This is a radiograph where a contrast agent (i.e. similar to dye) is put into the space surrounding the spinal cord so that the outline of the spinal cord can be appreciated.

Do you have to operate?
Many cases will do well when managed conservatively (see below) however in cases with paralysis the prognosis is better with surgery i.e. the dog or cat is more likely to regain walking function and be pain free; is more likely to improve quickly; and is less likely to have recurrences. Cases where pain sensation is absence (i.e. when the toe is pinched hard but the dog or cat is unaware of discomfort) are a surgical emergency and have a poor prognosis for improvement.

 

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