AffectedAnimals:
Dogs are most often affected; rarely cats may develop a similar disease process. Male dogs are more likely to have disk degeneration than females. Factors that increase the risk of disk degeneration include genetic predisposition, excessive weight, and lack of muscular fitness.

Breeds genetically predisposed to degenerative disk disease include those affected with chondrodystrophy, or abnormal cartilage development. Affected breeds include dachshunds, beagles, cocker spaniels, Pekingese, French bull dogs, basset hounds, Welsh corgis, small poodles and other mixed-chondrodystrophoid breeds.

Large, older dogs without chondrodystrophy may also develop degenerative disk disease.

Overview:
Intervertebral disks connect the vertebrae, or bones, of the spinal column together. These disks provide flexibility and support. Degeneration of an intervertebral disk may lead to protrusion, or bulging, or it may cause herniation, or rupture. Pain and weakness or paralysis may occur, depending on the degree of damage to the spinal cord. Damage is the result of both mechanical compression of spinal tissue and secondary reactive vascular and chemical changes within the tissue. This damage to tissues results in disruption of normal spinal cord function.

Small dogs, especially those with faulty development of the cartilage, termed chondrodystrophy, are prone to sudden disk ruptures and to a rapid onset of symptoms. Large dogs are much more likely to have gradual disk protrusions with slowly progressive pain and weakness, although they can also experience rapid herniations. Dogs with symptoms of disk herniation should be evaluated immediately by a veterinarian.

Diagnosis of a disk herniation is confirmed with x-rays and/or a myelogram, which is a special dye study that allows precise localization of spinal cord lesions. Depending on the severity of the case, and the overall condition of the affected dog, treatment may involve medication or surgery. Many dogs with disk ruptures recover. However, in very severe cases, in which the dog has lost the ability to feel deep-tissue pain, the paralysis may be permanent.