What Is Spondylosis Deformans?
Spondylosis deformans is a degenerative condition of the spine in which bony outgrowths — called osteophytes or bone spurs — develop on the undersurface of the vertebral bodies. Over time, these spurs can grow toward one another from adjacent vertebrae, and in some cases they bridge the intervertebral space entirely, forming what is described as a bony bridge. This bridge effectively fuses two or more vertebrae together at their ventral (lower) surfaces.
The condition is most commonly identified as an incidental finding on X-rays taken for other reasons — a routine pre-anaesthetic check, an investigation of abdominal signs, or a general health screen. Many dogs with spondylosis on their X-rays have no obvious signs of spinal pain at all, and for these animals no treatment is required beyond routine monitoring.
Spondylosis is not the same as intervertebral disc disease (IVDD) and should not be confused with degenerative myelopathy (DM), though the conditions can occasionally coexist. Understanding the distinction matters because the clinical implications, prognosis, and management are quite different.
How Does It Differ From IVDD and Degenerative Myelopathy?
Intervertebral Disc Disease (IVDD)
IVDD involves the intervertebral discs — the cushioning structures that sit between each pair of vertebrae. In disc disease, the soft material inside the disc either degenerates and bulges into the spinal canal (Hansen Type I, more common in chondrodystrophic breeds such as Dachshunds and French Bulldogs) or the outer fibrous layer of the disc gradually protrudes over time (Hansen Type II, more common in large breeds). IVDD can cause sudden or progressive neurological signs, including weakness, incoordination, and paralysis. Spondylosis, by contrast, involves bony changes at the edges of the vertebrae rather than disc herniation, and rarely causes neurological deficits.
Degenerative Myelopathy (DM)
DM is a progressive, fatal neurological disease caused by degeneration of the spinal cord itself. It is genetic in origin and predominantly affects German Shepherds, though other breeds including Boxers, Rhodesian Ridgebacks, and Welsh Corgis are also at risk. DM causes a slow, painless progression of hind limb weakness that eventually becomes paralysis. The critical distinction from spondylosis is that DM is not painful, whereas spondylosis when symptomatic typically causes back pain. Genetic testing is available for the SOD1 gene mutation associated with DM.
Which Breeds Are Most Affected?
Spondylosis deformans is more prevalent in large and giant breeds and tends to be associated with advancing age. Breeds with a higher reported incidence include:
- German Shepherds
- Boxers
- Airedale Terriers
- Labrador Retrievers
- Golden Retrievers
- Large mixed breed dogs
In some studies, spondylosis has been found in the majority of older large breed dogs examined radiographically, which reinforces the view that it is a normal part of spinal ageing in many animals rather than an inherently pathological process. The thoracolumbar junction — the area where the thoracic and lumbar spine meet — and the lumbosacral region are the most commonly affected sites, though lesions can occur anywhere along the spine.
Why Are Most Dogs Asymptomatic?
The reason that spondylosis so rarely causes clinical signs is largely anatomical. The bony bridges that form in spondylosis develop on the ventral aspect of the vertebrae — underneath them — away from the spinal cord and the nerve roots that exit the spine. As long as the osteophytes grow ventrally and laterally rather than encroaching on the spinal canal or the foramina through which nerve roots pass, the nervous system remains uncompressed and function is unaffected.
In fact, in dogs where extensive bridging spondylosis develops between multiple vertebrae, the fused segments may actually become more stable and less painful over time, as the movement at those joints — which is often what generates pain in active spondylosis — is progressively restricted by the bony fusion itself.
When Does Spondylosis Cause Problems?
A minority of dogs with spondylosis do experience clinical signs. These typically arise when:
- Osteophytes grow in a direction that impinges on nerve roots or the spinal canal
- Active bone spur formation is accompanied by local inflammation
- The condition occurs alongside other spinal disease, such as facet joint arthritis or IVDD at adjacent levels
- A bony bridge fractures, usually following trauma or abnormal loading
Signs of symptomatic spondylosis include back pain — the dog may cry out when touched along the spine, resist being lifted, or show reluctance to bend and turn — along with stiffness, reduced range of motion, difficulty rising from rest, and an unwillingness to exercise. In rare cases where nerve root compression occurs, signs can include muscle wasting, abnormal reflexes, or referred pain extending into a limb.
Diagnosis
Plain X-rays (radiographs) are usually sufficient to identify spondylosis. The characteristic ventral osteophytes and bony bridges are clearly visible on a lateral (side-on) spinal view. Multiple sites are commonly affected simultaneously, and the severity can range from small projections to extensive bridging across many vertebral segments.
If neurological signs are present or IVDD needs to be excluded, advanced imaging with CT or MRI is required. These modalities allow detailed assessment of the spinal canal, intervertebral discs, and nerve roots — information that plain X-rays cannot provide.
Managing Symptomatic Spondylosis
For the majority of dogs — those without clinical signs — no treatment is necessary beyond owner awareness and routine veterinary monitoring. Weight management and avoiding activities that place excessive stress on the spine are sensible precautions.
For dogs experiencing pain or stiffness, several management strategies are available:
- Non-steroidal anti-inflammatory drugs (NSAIDs) are the first-line medical treatment for spinal pain and are effective in most cases when used at the appropriate dose under veterinary supervision
- Other analgesic medications, including gabapentin or amantadine, may be added for chronic pain management where NSAIDs alone are insufficient
- Physiotherapy is highly beneficial for dogs with spondylosis-associated stiffness; targeted exercises improve core muscle strength, which helps support and stabilise the affected spinal segments
- Hydrotherapy, particularly underwater treadmill therapy, provides excellent low-impact exercise that maintains fitness and mobility without placing undue stress on the spine
- Acupuncture has a growing evidence base for musculoskeletal pain management in dogs and may be a useful adjunct for dogs with chronic back pain
The Outlook for Dogs With Spondylosis
The prognosis for dogs with spondylosis deformans is generally very good. The vast majority of affected dogs never require treatment and live full, active lives unaware that their spines have changed. Even in dogs that develop symptoms, a combination of appropriate analgesia, physiotherapy, and lifestyle adjustment is usually sufficient to maintain a good quality of life. Spondylosis is a manageable part of ageing in many dogs — not a diagnosis to fear, but one to monitor and address sensibly if and when signs appear.