The average dog and cat has seven bones in their neck, 20 in their back and three in the sacrum (bones that pass through and connect to the pelvis). They also have anywhere from 5 to 23 bones in their tails. That’s a total of somewhere between 35 and 58 spinal vertebrae/bones. The most important are the first 30 from the back of the skull to the top of the tail.

These bones provide a bony cage through which the delicate nervous tissue of the spinal cord travels. With the exception of the three sacral bones, which are fused, the rest of these vertebral bones articulate, moving against each other to allow curvature and movement of the spine. They are cushioned between each other by shock-absorbing, intervertebral discs that absorb compression and stress to the spine.

Compression on the spinal cord can cause intense pain or permanent paralysis
One of the more common problems is when a disc ‘prolapses’. This is usually when the outer fibrous part of a disc tears or fissures and the soft gel-like interior is propelled into the space where the nerves travel. This is known as Hansen type-I disc disease. Alternatively, the outer part of the disc (the annulus) itself can bulge into the spinal cord and impinge on the nerves. This is known as Hansen type-II disc disease.

Compression on the spinal cord can cause intense pain, temporary nerve damage or, in extreme cases, permanent paralysis. Treatment might be conservative with powerful anti-inflammatories and pain relief to treat the symptoms. This is more likely when there isn’t significant nerve function impairment. If spinal cord damage is significant then surgery to relieve pressure from a ruptured or bulging disc may be required. Diagnosis is usually achieved with radiography, or more accurately with MRI or CT imaging of the individual discs.

Back disease can be as problematic in pets as it is in humans
Whether surgery is indicated or conservative treatment is chosen, back disease can be recurrent and as problematic in pets as it is in humans. Weight management, physiotherapy and rehabilitation are key to long term success.