Intervertebral Disc Disease (IVDD) is a condition where the spine 'herniates' which means the spinal cord compresses, causing lasting and debilitating damage. The intervertebral discs act as shock absorbers between the vertebrae, providing cushioning, are supportive and allow for flexibility in the spine. IVDD occurs when these discs degenerate or herniate, leading to spinal cord compression and neurological symptoms.
There are two main types of IVDD in dogs:
- Hansen Type I: This happens when the soft, jelly-like centre of the spinal disc becomes hardened over time. With one wrong jump or sudden impact, this rock-like disc shoots out of its thick shell and pushes upward into the spinal cord and its surrounding nerves. This movement of the disc material (called a herniation) causes compression and bruising of the spinal cord, and therefore can also cause paralysis. Because of its action, Hansen Type I is characterised by sudden, sharp pain but the degree of damage and consequent disability varies. This form of IVDD is more commonly seen in chondrodystrophic breeds (dogs with long backs but relatively short legs) such as Dachshunds, Shih Tzus and Corgis.
- Hansen Type II: This type is a slower, degenerative process where the soft disc material intrudes on the spinal cord and spinal nerves over time, this can be either months or years. What happens is the thick fibres around the soft disc material will slowly collapse over time and push upwards, thus causing more chronic, long-term pain and spinal cord compression. This in turn causes progressive paralysis. This form of IVDD is more common in larger breeds of dogs such as German Shepards, Labradors and Dobermans.