Discospondylitis is a bacterial or fungal infection of the intervertebral disc and adjacent vertebral endplates, and it's a frequently missed cause of progressive back pain, reluctance to move, and fever in middle-aged large-breed dogs. Blood culture is positive in roughly 75 percent of cases and identifies the offending organism — usually Staphylococcus or Brucella canis (Burkert et al., 2005, JAVMA). With 6 to 12 months of appropriate antibiotics most dogs recover well, but missing the diagnosis lets infection erode the spine and damage the spinal cord.
Last reviewed: June 2026
What Discospondylitis Is
Discospondylitis is infection of the disc space (intervertebral disc) and the adjacent vertebral endplates. Bacteria reach the disc hematogenously — usually from a distant skin infection, urinary tract infection, dental disease, or endocarditis. The infection erodes the bony endplates, causes inflammation and pain, and can collapse the disc space. Large- and giant-breed intact male dogs are over-represented. As detailed in Greene's Infectious Diseases of the Dog and Cat, the lumbosacral and mid-thoracic regions are most commonly affected.
Signs Owners First Notice
The cardinal sign is progressive back pain. Owners describe a dog who arches the back, refuses to jump, vocalizes when picked up, walks stiffly, and develops a hunched posture. Fever (38.9°C / 102°F or higher) is present in roughly half of cases. Many dogs have unexplained weight loss, decreased appetite, and lethargy. As infection erodes the endplates, neurological signs appear: hindlimb weakness, ataxia, knuckling, urinary or fecal incontinence in advanced cases. Pain on direct palpation of an affected vertebra is the most specific physical finding.
Causes and How Infection Reaches the Spine
The most common organisms are Staphylococcus pseudintermedius and Staphylococcus aureus from a peripheral source. Brucella canis is an important cause especially in intact dogs from breeding kennels — every discospondylitis workup should include Brucella testing because it is zoonotic and changes management. Streptococcus, E. coli, and fungal organisms (Aspergillus in German Shepherds) are also reported. The 2018 ACVIM consensus on canine brucellosis emphasizes screening any dog with discospondylitis to prevent human transmission.
How It's Diagnosed
Radiographs show classic endplate lysis and irregularity, often most evident at 2 to 4 weeks after onset — earlier imaging can be normal, which is why MRI is preferred when discospondylitis is strongly suspected. Blood culture identifies the organism in roughly 75 percent of cases; urine culture and Brucella serology are routine (Burkert et al., 2005, JAVMA). CSF tap and culture is added when neurologic signs are present. Echocardiography is reasonable when endocarditis is suspected as the source.
Treatment
Long-course antibiotics — typically 6 to 12 months — based on culture and sensitivity are the foundation. While awaiting cultures, empirical cephalexin or amoxicillin-clavulanate is reasonable for suspected Staphylococcus. As described in Plumb's Veterinary Drug Handbook, treatment is continued until radiographic resolution and full clinical recovery. Pain management with NSAIDs and gabapentin is essential during the early weeks. Surgical decompression is reserved for dogs with progressive neurologic deterioration or pathologic fracture.
When to See a Vet
Call your vet today if:
- Progressive back pain, refusal to jump, or hunched posture for more than a few days
- Fever combined with reluctance to move
- Persistent unexplained back pain in an intact male large-breed dog
- A dog with a recent skin or urinary infection develops back pain
- Recurrent UTIs with new lameness or stiffness
Go to the ER immediately if:
- Sudden hindlimb paralysis or knuckling
- Loss of urinary or fecal control
- Severe fever (above 40°C / 104°F) with collapse
- Severe pain not controlled by previously effective medications
- Bleeding wounds, signs of sepsis, or unresponsiveness
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Frequently Asked Questions
Can my dog give my family Brucella canis?
Yes — Brucella canis is zoonotic and can cause persistent infection in humans, particularly immunocompromised people, children, and pregnant women. Every dog being worked up for discospondylitis should have a Brucella titer or PCR. Positive dogs require careful handling, are typically not treated to cure, and counseling about household exposure is essential.
How much does diagnosis and treatment cost?
Initial vet exam typically runs $50 to $150 in the US. Plain radiographs cost $150 to $400. MRI of the spine ranges $1,500 to $3,500 at a specialty hospital. Blood and urine cultures add $200 to $400. Brucella testing is $80 to $200. A 6 to 12 month course of culture-directed antibiotics runs $40 to $200 per month depending on agent. Quarterly rechecks add $150 to $400 per visit. Decompressive surgery, when needed, is $4,000 to $8,000. Catching it early before neurologic damage is dramatically cheaper than surgery.
How long until my dog feels better?
Pain typically improves within 5 to 14 days of starting appropriate antibiotics. Many dogs return to nearly normal activity within 4 to 6 weeks, but full course antibiotics must be completed for 6 to 12 months to prevent relapse. Early stopping is the most common reason for recurrence.
Will the spine recover its structure?
Radiographic improvement is slow and often incomplete — the endplates remain irregular for life. Functionally, however, most dogs return to comfortable normal activity. Adjacent vertebrae often bridge with reactive bone, which provides natural stabilization.
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