41 UMN
Intervertebral disc disease
INTRODUCTION
The anulus fibrosis of the intervertebral disc may rupture or bulge, and compress the adjacent spinal cord, nerve root, or both. Normal activity is sufficient to precipitate IVDD in a degenerate disc (Figs 41.1 and 41.2 and see Table 41.1).
Table 41.1 The nature of the anulus pathology has been categorized as type I or type II
Type I | Type II | |
---|---|---|
Pathology | Tear, rupture | Bulge, prolapse |
Breed |
Signs may occur suddenly or gradually. They can resolve with time and rest, or progressively worsen. Pain is a common sign, occurring in 60–70% of affected dogs (Table 41.2).
Table 41.2 Signs of disc disease
Cervical | Thoracolumbar | |
---|---|---|
Location | All, except C1–2 | Caudal to T9–10 |
Common presentation | ||
Pain perception | Intact | May be absent |
Respiration | ± Hypoventilation | Unaffected |
Cats are also affected by spontaneously occurring Type I disc disease. Type II is found as an incidental finding at post-mortem. The range of clinical presentations is similar to the dog. Pain may or may not accompany feline IVDD. The age range for feline IVDD is wide: 4–17 years, with most affected before 8 years of age.
The following cases of two dogs with hindlimb ataxia illustrate the differences in localizing lesions between large and small breed dogs.
CLINICAL EXAMINATION
Clinical examination showed a quiet but mentally responsive ambulatory dog with an arched back, lowered head posture, hindlimb ataxia and a shortened stride in both forelimbs. While sitting, the dog was seen to knuckle the right fore and not correct this abnormal posture. Hindlimb hopping was decreased. Spinal reflexes were increased in the hindlimbs and normal in the forelimbs. No thoracic, lumbar, or lumbosacral pain could be elicited. The abdomen was relaxed. The neck was tense but the dog was muzzled and this may have been a pain response or a behavioural response to being handled.
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