What is intervertebral disc disease?

Intervertebral disc disease is diagnosed when a disc of the spinal column fails and pushes disc material into the spinal canal. This results in compression and damage to the spinal cord or nerves which can lead to pain or paralysis.

There are generally two types of intervertebral disc disease. Type I occurs mostly in small dogs and involves rupture of the center of the disc into the spinal canal. Type II occurs in any size dog and involves “prolapse” or slipping of the outer portion of the disc into the spinal canal.

What is the cause of disc disease?

Type I disc disease is by far the most common and is associated with abnormal degeneration of the center of the disc. This portion of the disc is called the nucleus pulposus. The nucleus is supposed to be a soft gel material that can serve as a shock absorber for the spine during day-to-day activities. In many small dogs and particularly in Dachshunds the nucleus degenerates or dries out. So, instead of the nucleus being a gel like material it is more like small grains of sand.

The degenerated disc cannot handle normal activ­ity and sometimes it explodes out of the disc space and into the spinal canal. When this occurs the spi­nal cord can be compressed, bruised, or severely damaged. In mild cases the dog will experience just pain. In more severe cases the dog loses strength in the limbs and in the most severe cases the dog loses sensation in the limbs.

Type II disc disease can happen in any size or breed of dog but appears to be more common in larger breeds. In type II disc disease the outer portion (called the annulus) may slip into the spinal canal causing pressure on nerves or the spinal cord. As with type I disc disease the signs can be as mild as pain or as severe as paralysis. The causes of type II disc disease may be genetic in certain breeds or it may be caused by trauma or degeneration of the disc.

What are other causes of spinal disease?

There are several other disease that can cause signs similar to disc rupture. These include:
Inflammatory diseases – diseases such as GME or steroid responsive meningitis are diagnosed by spinal tap and can cause signs identical to disc rupture. They are treated by steroid medication
FCE – sometimes referred to as a spinal stroke, FCE (fibrocartilagenous embolic myelopathy) has signs similar to disc disease but is treated with rest and time
Cancer – cancer can appear identical to disc disease. Some cancer is treated with medications while others are treated with surgeryDegenerative diseases – degenerative diseases may appear similar to disc disease. Treatment of these diseases is very difficult.

How is disc disease treated?

Medical treatment

If a dogs only sign of disc disease is pain, it is often treated with rest and analgesics. Other medications that are frequently diagnosed include ste­roids and muscle relaxants. The use of steroids is controversial and they must be used with caution as they can lead to stomach or intestinal ulcers. It is important for owners to understand that the most important treatment for disc disease is rest and not the medication!!!
If the back pain persists for more than a week or if it is particularly severe as may happen with disc disease in the neck, then surgery should be considered.

Surgery

Surgery should be considered for severe or long term pain or in cases where the dog shows more severe signs such as ataxia (falling over), weakness, or paralysis. In these cases the chance of complete recovery is greatly improved; however, if surgery is going to be performed it should be performed as soon as possible to maximize the chances of a full recovery.
Surgery for disc disease in the neck is called a “ventral slot”. In this procedure we make a small hole through the disc space from the bottom of the neck to remove the disc material in the spinal canal. Rarely we will perform spinal surgery of the neck from the top (dorsal). This is most often done to treat cancer.
Surgery for disc disease over the back (thoraco-lumbar) is done from the back. A small hole is made in the side (hemilaminectomy) or the top (dorsal laminectomy) of the spine to remove the disc material from the spinal canal. This is the most common form of spinal surgery.

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