Several infectious agents have been isolated from diskospondylitis cases in animals including Staphylococcus intermedius, Brucella canis, Corynebacterium spp, Streptococcal spp, Escherichia coli , Pasteurella spp, Nocardia-like organisms and various fungal infections. Fungal infections are very rare in the UK but is seen in other countries such as the USA. The bacterium Staphylococcus intermedius is the most common isolate from cultures taken from dogs with diskospondyitis. Sometimes the infection is secondary to a penetrating foreign body, such as grass seeds.
The route by which the site becomes infected varies. In many cases the infection spreads via the blood system. Diskospondylitis may be secondary to infection at another site in the body, such as dental disease, prostate or urinary tract infections.
The diagnosis is confirmed by X-rays which shows the characteristic changes of a collapsed joint space with bone destruction in the end plates of both adjacent vertebrae. This results in dark (radiolucent) areas (called lysis), with a reactive white (radiodense) region of new bone (called sclerosis) next to it. Often there is bridging spondylosis between the vertebrae. These radiographic changes can be seen about 4-6 weeks after the infection establishes itself in the disk space.
A special imaging technique called scintigraphy is available in some specialist veterinary centres and this can help a clinician to identify the disease at an earlier stage than conventional X-rays.
Accurate treatment may necessitate the identification of the organism causing the infection by culturing blood, or culturing samples aspirated or taken by biopsy directly from the infected site. About 75% of cases are reported to have positive blood cultures so invasive procedures should not be necessary in the majority of cases. Brucellosis should be screened for by blood test and titres over 1:250 are considered significant and represent bacteraemia, whereas lower titres reflect previous exposure to the organism.
Following culture and sensitivity the most appropriate bactericidal antibiotic is used and may need to be given for at least 4-6 weeks. Affected animals should be rested with minimal exercise during this period.
If a foreign body is present this has to be removed surgically or the infection will probably recur despite appropriate antibiotic therapy.
Sometimes surgical curettage is needed at the site to remove chronically infected tissue and facilitate local administration of anti-infective agents.
The prognosis is good for most cases, unless involvement of the spinal cord causes severe neurological problems. Brucella infection is difficult to treat completely and recurrence is likely.
The prognosis is always best the earlier the diagnosis is made and treatment can be instituted.
Long term problems
Updated January 2016