Neurology Service

Intervertebral Disk Disease

This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian.

Intervertebral Disk Disease

The intervertebral disks sit between the vertebrae in the spine. They function as shock-absorbers to help dissipate the forces placed on the spine. Each disc is made up of two parts, an outer fibrous covering (the annulus fibrosus) and an inner, gelatinous portion, the nucleus pulposus.

Invertebral disc disease (IVDD) occurs when there is degeneration of the intervertebral disks. As disks degenerate, they lose some of their water content, the nucleus becomes less gelatinous and more calcified. This calcified disc is less stable and more apt to herniate (type I IVDD) or protrude (type II IVDD). Discs usually rupture or protrude in an upward direction. Sitting above the disc anatomically is the spinal cord.

Type I IVDD can occur in any area of the spinal cord. Dachshunds and other chondrodystrophic dogs (dogs with short legs and longer bodies) appear predisposed, as their disks age or degenerate more readily than most dogs. Young to middle-aged dogs are most commonly affected. Dogs less than 1 year of age rarely have intervertebral disc disease. Middle-aged to older large breed dogs can also develop disk disease (usually type II IVDD). Disc disease, in general, is rare in cats.

Signs of spinal cord disease (anything from back pain, to weakness in the limbs to paralysis of the limbs) develop due to the force of the disk material hitting the spinal cord, or because of the amount of disk material that enters the spinal canal and compresses the spinal cord. The more spinal cord damage, the more severe the clinical signs. The most important determinant of prognosis in a dog with IVDD is the ability to consciously feel their limbs. If a patient can still feel his limbs, even if he can no longer move his legs, there is an 80-85% that, if surgery is performed, he will have a functional recovery and be able to walk again.

IVDD is suspected as a diagnosis based on physical and neurologic exam findings, breed and history. To definitively diagnose IVDD, spinal x-rays, and either a CT scan or MRI of the spine are performed. Anesthesia is required to perform the latter two diagnostic procedures. Following advanced imaging, and the diagnosis of IVDD, surgery is then, sometimes, pursued. . General guidelines have been established for therapy depending upon severity of clinical signs. Mildly affected animals (animals back pain alone or those with mild weakness who are able to strongly walk) may be managed medically. Medical management entails strict cage confinement and appropriate pain medications for a total of 6-8 weeks. Confinement is very important to allow for healing of a degenerative disk. If, despite appropriate medical management a patient’s back pain is refractory or if the patient’s neurologic status worsens, surgery is pursued. Surgery is usually recommended in cases where animals are more severely affected (those who are unable to stand and walk). The goal of surgery is the removal of the extruded (type I IVDD) or protruded (type II IVDD).and subsequent relief of spinal cord compression.

This information was made possible by funds from the Neurology Endowment at Washington State University.

Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.

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