Spondylosis Deformans in Cats
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 of the spine. A bony spur may develop in a single spot on the spine; more commonly, there will be multiple bone spurs in several different locations along the spine. In cats, spondylosis deformans lesions are often found along the thoracic spine (along the top of the rib cage), although they also may develop in the lumbar or sacral areas (lower back). 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 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.
If the intervertebral discs become damaged, the joints between them become less stable, resulting in abnormal motion. With spondylosis deformans, the intervertebral discs slowly degenerate as part of the aging process and the condition is not associated with inflammation. The bone spurs of spondylosis deformans develop to re-establish the stability of the weakened joint or joints.
The formation and growth of the osteophytes or bone spurs are 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 cats?
No, any middle-aged to older cat can be affected. In most cats, this degenerative condition will begin to develop by 10 years of age, and some researchers feel that every cat that lives long enough will develop this condition.
What are the symptoms of spondylosis deformans?
Most cats with spondylosis deformans are free of any symptoms. Occasionally, the bone spurs restrict the movement of the spine and the cat may appear to be stiffer or the spine may not appear to be 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 cat may cry out when touched along affected areas of the back.
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. Congenital bone deformities and traumatic injury to the spine are some examples of other conditions that can trigger the development of osteophytes. 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.
Since there is no difference in the radiographic appearance of a bone spur that results from spondylosis deformans and one that results from an inflammatory lesion, multiple x-rays may be needed to thoroughly assess the spine and identify radiographic patterns that indicate other causes of instability. This is especially important if the cat is showing any symptoms of nerve damage or appears to be in pain.
Other tests that may be recommended include a Myelogram and/or Magnetic Resonance Imaging (MRI). In some cases, your veterinarian may recommend referral to an orthopedic specialist for further diagnostics and/or treatment.
How is spondylosis deformans treated?
Treatment recommendations depend on the individual cat and whether or not it is showing any clinical signs.
Most cats with spondylosis deformans appear to be pain-free and in these cases treatment is not necessary. If the pet appears to be painful, non-steroidal anti-inflammatory drugs (NSAIDS) or other analgesics may provide relief. Weight loss 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 entire lifetime of the cat. Many affected cats live satisfactory lives, even though they may eventually develop some limitations in flexibility and range of motion. Your veterinarian will discuss the prognosis for your individual cat, based on the results of diagnostic testing and/or the response to treatment.