Intervertebral Disc Disease

Here's an article that explains Claire's exact diagnosis, Intervertebral Disc Disease.

Reprinted from
http://www.vetmed.wsu.edu/cliented/ivd.aspx
Written by the College of Vetrinary Medicine at Washington State University

What are Intervertebral Disks?

The intervertebral disks sit between the vertebrae in the spine. They act like shock-absorbers to help dissipate the forces placed on the spine. They have two portions, an outside fibrous covering ( the annulus fibrosis) and an inside, more gelatinous portion, the nucleus pulposis. In this way they kind of resemble a jelly donut. The outside of the donut is the annulus, and the jelly on the inside is like the nucleus pulposis

When the intervertebral disks become damaged, this is referred to as intervertebral disk disease ("Disk disease", "Slipped disk"). As disks age, they lose water content, and become less able to withstand compression. They become less able to withstand forces placed upon them. If too much force is placed on them, they can be squeezed and expand or rupture. This rupture usually occurs in an upward direction, and the disk extrudes into the spinal canal where the spinal cord is. Signs develop either because of the force of the disk material hitting the cord, or due to the disk material compressing the spinal cord.

Intervertebral disk disease can occur in any area of the spinal cord. Dachshunds appear predisposed, as their disks age or degenerate quicker than most dogs. Young to middle-aged dogs are most commonly affected. Dogs less than 1 year of age rarely have intervertebral disc disease. Geriatric dogs are occasionally affected. Clinical signs of disk disease are rare in cats.

Signs of a disk problem range from being painful to being unable to move. The more spinal cord damage, the worse the clinical signs. Animals with the worse spinal cord damage from disk disease lose the ability to move and to feel (conscious sensation) their limbs. To know if an animal can consciously feel, we have to pinch the toes and see if the animal vocalizes or tries to bite us. While this test may seem harsh, it is very important. If an animal has lost the ability to feel in the legs, its chance of walking again is about 50%. If an animal can still feel in the legs, even if they can't move, there is a 75% chance or greater that the animal can walk again if surgery is performed.

The diagnosis of disk disease is based on clinical signs initially. To prove that a disk is pressing on the spinal cord, a special X-ray study known as a myelogram is often necessary. To perform a myelogram, first a spinal tap is done. Next, a dye or contrast agent is injected around the spinal cord to outline it. This usually shows where the spinal cord is damaged, and helps the surgeon to know exactly where the surgery should be performed. For both the myelogram and the spinal tap the animal needs to be very still, therefore anesthesia is necessary to perform these tests.

CT or MRI are other techniques that can be used to see the ruptured disk.

General guidelines have been established for therapy depending upon severity of clinical signs. Mildly affected animals (animals with pain alone or mild weakness but able to walk) may be managed with cage confinement for at least two weeks. Strict confinement is very important to allow for healing of a partially damaged disk. If after 2 weeks signs are not improved, diagnosis and surgery should be considered. If the animal worsens during this time, surgery should be considered sooner.

If improvement is noted, continuation of cage confinement is indicated for up to one to two weeks after the animal is clinically normal.

More severely affected animals (those who are unable to stand and walk) are considered for surgery. The surgery is performed to remove extruded disk material from around the spinal cord, relieving the compression and giving the spinal cord the best chance at healing.

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