Overview
Discospondylitis is an infection that affects the discs between the bones of the spine (called intervertebral discs) and the ends of the bones themselves. In more severe cases, the infection can spread to the meninges (the protective covering of the spinal cord) or form a pocket of pus inside the spinal canal.
Causes
This condition most commonly develops when a bacterial infection in another part of the body—like the urinary tract, skin, or from a deep wound—travels through the bloodstream and settles in the spine. The bacteria most often involved include Staphylococcus, Streptococcus, and E. coli.
A less common but very important cause is a bacteria called Brucella. This infection is serious because it can be passed to other animals and to people, especially those who are very young, elderly, or have weakened immune systems.
Fungal infections, such as Aspergillus or Cryptococcus, can also cause discospondylitis. These fungi usually enter the body through the nose or mouth, then spread through the bloodstream to the spine.
It’s important to know that in many cases, even with extensive testing, the original source of the infection is never found.
Clinical Signs
The most common and consistent sign of discospondylitis is severe back pain. Your pet may cry out, seem stiff, or be very reluctant to move or jump. In more serious cases, you might notice wobbliness, weakness in the legs, or even signs of paralysis—especially if an abscess forms or the spine becomes unstable.
Diagnosis
The best way to diagnose discospondylitis is through an MRI scan. In more advanced cases, it might also show up on spinal x-rays.
Once discospondylitis is suspected or confirmed, we often may recommend additional tests, including blood or urine cultures, infectious disease screening, and sometimes a spinal tap to help identify the cause. Unfortunately, even with thorough testing, the specific organism is found in only about half of the cases.
Treatment
Treatment for discospondylitis involves a prolonged course of antibiotics—often for a year or more— and a sustained period of pain management. Treatment is ideally based on test results identifying the infection. However, when no specific organism is found, treatment is based off response to broad spectrum antibiotic therapy.
In cases involving Brucella, it’s important to know that dogs can carry the infection for life, even if their symptoms improve. Because Brucella can infect other animals and immunocompromised people, euthanasia may need to be considered in certain situations to protect human health and other animals.
Dogs with fungal infections usually require indefinite antifungal medications, and sadly, they often do not respond well to treatment.
Surgery is rarely required but may be recommended if an abscess is placing significant pressure on the spinal cord or if the spine becomes unstable. It may also be considered to obtain tissue samples when diagnostic tests fail to identify the cause of infection and the pet is not improving with medical treatment.
Follow-up imaging is often recommended to confirm that the infection has resolved and to determine when it is safe to discontinue treatment. This typically involves either annual MRI scans or spinal X-rays performed every few months.
Prognosis
For most animals with bacterial discospondylitis, the prognosis is good if treatment is started early and continued long enough. The prognosis is more guarded in cases caused by Brucella or drug-resistant infections. Fungal discospondylitis often carries a poor prognosis, as they tend to be poorly responsive to treatment.