What is spondylosis deformans?
Spondylosis deformans is a condition that affects the vertebral bones of the spine and is characterized by the presence of bony spurs or “osteophytes” along the edges of the bones. A bony spur may develop in a single spot on the spine or, more commonly, there will be multiple bone spurs in several different locations along the spine.
The most common places that spondylosis deformans develops are along the thoracic vertebrae (chest), especially at the junction between the rib cage and the abdomen; in the lumbar spine (lower back); and in the lumbosacral spine (around the hips and pelvis). In some cases, the bony spurs may become large enough that they appear to form a complete bridge between adjacent vertebral bones.
What causes spondylosis deformans?
Spondylosis deformans is a chronic condition that is associated with aging. Research indicates that it often develops as a secondary problem related to a degenerative disease of the intervertebral discs.
In the normal spine, the vertebral bones are joined by ligaments to form a flexible protective column around the spinal cord. There is an intervertebral disc between each vertebral bone, and these discs act as shock absorbers and cushions. The series of joints that make up the spine give the back flexibility of motion while protecting the delicate spinal cord from damage.
"Spondylosis deformans is a chronic condition that is associated with aging."
If the intervertebral discs become damaged or degenerate over time, the joints between them become less stable, resulting in abnormal motion. The bone spurs of spondylosis deformans develop to re-establish the stability of the weakened joint or joints. Aging, repetitive microtrauma through activity, major trauma, or a genetic predisposition can lead to this condition. It is not associated with inflammation.
The formation and growth of bone spurs is triggered by instability, and it appears that they grow only as large as is necessary to reinforce the diseased joint.
Is spondylosis deformans more common in certain breeds of dogs?
Although this condition was once thought to be more common in large-breed dogs, any middle-aged to older dog can be affected. In most dogs, this degenerative condition will begin to develop by 10 years of age, and some researchers feel that every dog that lives long enough will develop this condition. Boxers, German shepherds, and flat-coated retrievers seem to be predisposed.
What are the symptoms of spondylosis deformans?
Most dogs with spondylosis deformans are free of any symptoms. Occasionally, the bone spurs restrict movement of the spine, and the dog may appear to be more stiff, as the spine is not as flexible. If a bone spur grows near a nerve root as it comes out of the spinal canal, it may put pressure on the nerve, causing pain or lameness. If the condition is painful, the dog may whine, cry, or flinch when touched along affected areas of the back, they may limp, have difficulty getting up and down, and be reluctant to jump.
Can other conditions cause bone spurs or osteophytes on the spine?
Any other condition or disease that causes instability to the spine can stimulate the development of osteophytes, including birth defects affecting the vertebral bones, trauma that causes a fracture or luxation, infection such as discospondylitis, and spinal surgery. In these cases, inflammation plays a role in the development of the bone spurs that form around the injured or unstable joint.
How is spondylosis deformans diagnosed?
This condition is usually diagnosed from X-rays of the spine. In some cases, it may be an “incidental finding” that is noticed when X-rays are taken for some other reason.
There is no difference in the X-ray appearance of a bone spur that results from spondylosis deformans and one that results from an inflammatory condition, so additional testing may be needed to thoroughly assess the spine and identify other causes of instability.
"The discs and other soft tissues surrounding the vertebrae do not show up on X-rays,
so advanced imaging may be required."
This additional testing is especially important if the dog shows any symptoms of nerve damage or appears to be in pain. The discs and other soft tissues surrounding the vertebrae do not show up on X-rays, so advanced imaging may be required.
Other recommended tests may include magnetic resonance imaging (MRI), CT scan, or myelogram (contrast dye injected around the spinal cord). You will need a referral to an orthopedic specialist or a neurologist for these diagnostics and/or treatment.
How is spondylosis deformans treated?
Treatment recommendations depend on the individual dog and whether they are showing any clinical signs.
Most dogs with spondylosis deformans appear to be pain-free and in these cases, treatment is not necessary. If the pet appears to be in pain, non-steroidal anti-inflammatory drugs (NSAIDs) or other pain medications may provide relief. Physical therapy, weight loss, and controlled exercise programs may be helpful in some cases.
In rare cases, the osteophytes may be causing spinal cord compression, and in these cases, surgery to remove them may be indicated.
What is the prognosis for spondylosis deformans?
If there are no symptoms, spondylosis deformans may go undetected for years, or even for the dog’s entire lifetime. Many affected dogs live satisfactory lives, even though they may be somewhat limited in flexibility and range of motion. Your veterinarian will discuss the prognosis for your individual dog, based on the results of diagnostic testing and/or the response to treatment.