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Signs and Symptoms
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Between each of the vertebrae (bones of the spine) lies an intervertebral disc. This disc is composed of a soft tissue, called fibrocartilage, that allows movement and acts as a shock absorber. Normal wear and tear with aging results in deterioration of these discs (disc degeneration). Although some older patients can show clinical signs, more often the deterioration progresses without any problems or symptoms. In some pets, this deterioration is accelerated and middle-aged patients can show clinical signs.
Type I Disc Degeneration
Two groups of patients are most commonly affected. The first group is typically small breed dogs that are usually between the ages of 3 and 9 years. The center of the intervertebral discs, the nucleus pulposus, becomes calcified and rigid losing its normal elasticity. With a mild traumatic event, and occasionally even normal movement, the disc can rupture and the calcified center be rapidly extruded or herniated. If the disc ruptures to the sides or bottom, the result may only be transient pain lasting for a few hours to a few days. It may even be unnoticed by many owners; however, if the disc ruptures above, the calcified contents are extruded into the spinal canal and can impact on the spinal cord. This results in severe pain and varying degrees of paralysis. Immediate treatment is necessary or complete and permanent paralysis may occur. Surgery is necessary if medication alone does not work or if the signs are severe.
Type II Disc Degeneration
The second group of patients most commonly affected with disc degeneration are large breed dogs, usually 4 to 9 years of age. In these patients the disc degeneration results in a slowly protruding or bulging disc. The spinal cord may become compressed over the course of many months and thus symptoms may be gradual and be mistaken for arthritis. Treatment should be started before irreversible damage to the spinal cord has occurred. Again, the decision for medical treatment or surgery will depend on the severity of the symptoms and where in the neck or back the problem is occurring.
Traumatic Disc Rupture
Major traumatic events may also result in rupture of deteriorated or even normal discs in any patient. Treatment in patients with traumatic disc rupture may be the same as for those patients with Type I or Type II disc degeneration. This condition has also been called Fibrocartilagenous Embolism or FCE in the past.