Diskospondylitis refers to infection of the intervertebral disk and the adjacent vertebral endplates. Diskospondylitis is most frequently caused by bacteria, including E. coli, Staphylococcus, Streptococcus and Brucella. Occasionally diskospondylitis may be caused by fungal organisms. Male dogs are affected more frequently than females and large breed dogs are over-represented. The infection is usually widespread in the body, meaning it is present in other organs such as the urinary system or heart valves.
Any intervertebral disk can be affected, however, the L7-S1 disk is most commonly affected. Clinical signs depend on the spinal segment affected and may range from pain only to complete paralysis. Many affected dogs exhibit systemic signs including weight loss, poor appetite, and generally feeling ‘sick’.
Plain (non-contrast) radiographs are often diagnostic. The vertebral endplates are destroyed and irregular. The disk space may either appear widened or may be collapsed. Here is an example of a particularly extreme case of diskospondylitis.
Diskospondylitis is NOT spondylosis deformans which refers to smooth bridging between the vertebral bodies.
CT or MRI are indicated in cases where diskospondylitis is not apparent on plain radiographs or when weakness or ataxia is present. Other tests that may be warranted in cases of diskospondylitis include blood work (CBC, chemistry panel), urine tests including a urine culture and sensitivity (to find out which bacteria is the cause and which medicine is best to treat the infection), blood tests for Brucella, and potentially blood cultures or an ultrasound of the heart. Occasionally surgery may be indicated to remove the infection and obtain samples for culture and sensitivity.
Treatment of Diskospondylitis
Treatment typically involves antibiotics, which are ideally based on results of culture and sensitivity. Antibiotics should be prescribed for 6-8 weeks, as relapses are common if not treated long enough. Pain medications are prescribed since most dogs are quite painful. Occasionally surgery may be necessary.
Close monitoring and follow-up examinations are recommended. Repeating radiographs (X-rays) helps check for adequate healing (or continued infection).
Prognosis for Diskospondylitis
Prognosis depends on several things, including 1) type of infection (i.e. fungal infections tend to be worse than bacterial infections) and 2) how affected the patient is (paraplegic dogs that are unable to feel their back legs tend to have a worse prognosis than those that have less severe signs).
Diskospondylitis in a dog. T13-L1 and L1-L2 are involved. The caudal endplates of T13 and L1 and the cranial endplates of L1 and L2 are irregular.