Chondrodystrophy in dogs is defined by dysplastic, shortened long bones and premature degeneration and calcification of intervertebral discs.
This disease is therefore much more common in the chondrodystrophic breeds (that is short-legged breeds such as the dachshund, basset hound and corgi) and the dachshund accounts for 45 - 70% of all intervertebral disc disease (IVDD) in dogs. Chondrodystrophic breeds are prone to a type of disc degeneration called chondroid metaplasia, where the intervertebral discs in the spinal column become dried out, hardened and calcified at an early age.
The discs are then less able to flex with movement, and more prone to bulging or rupture. The calcified inner disc material puts pressure on the spinal cord, causing pain and damage to the nerves running through the spinal cord. Severe pain to paralysis can occur, as well as inability to urinate or defaecate, and disc ruptures in the neck can cause respiratory paralysis and death.
Signs of intervertebral disc rupture most commonly occur in chondrodystrophic breeds between 3-6 years of age. Calcification of discs is generally apparent on x-rays by 2 years. Ruptures can occur anywhere, but are more common in the upper back (65%), followed by the neck area (18%).
IVDD can occur in non-chondrodystrophic breeds as well, with the most commonly affected being German shepherd dogs, Labrador retrievers and Dobermanns. In these breeds disc rupture tends to occur later, at around 8 years of age on average. Obesity is also a major risk factor for IVDD.
Disc rupture is generally suspected from clinical signs of severe pain or neurologic deficits, and is confirmed via myelography (injecting dye into the spinal canal which is then visible on x-ray) or MRI. Plain x-rays are not diagnostic for disc rupture, however they may rule out other conditions. In less severe cases treatment may be successful with medication, nursing and strict cage rest for a number of weeks. With significant nerve deficits or any ongoing deterioration, surgical removal of the prolapsed disc is the treatment of choice. Recovery from surgery involves physiotherapy and good pain management, and if treated early the prognosis for IVDD is generally good.