a degenerative spinal condition in dogs.
Intervertebral Disc Disease (IVDD) is a degenerative disease seen most commonly in dog breeds with shorter legs and longer backs (chondrodystrophoid). The most commonly affected breeds are the Dachshunds Shih-Tzus, Beagles and Cocker Spaniels, however no dog is completely immune to disc disease. In rare instances trauma such as being hit by a car, shot or falling from a height can cause a traumatic rupture of a disc.
In the chondrodystrophoid breeds a genetic error in disc metabolism causes the interior portion of the disc (nucleus pulposus) to absorb calcium and other minerals which effectively limit the discs ability to act as a shock absorber between the vertebra.
A major difference between disc herniation in people and dogs is that in people the disc tends to move to the side, putting pressure on nerve roots, causing pain but not paralysis, where as in dogs the disc tend to herniate upward into the spinal canal putting pressure on the spinal cord and causing weakness or paralysis.
Intervertebral disc disease (IVDD) is a progressive disease both in the degeneration of the disc and the progression (severity) of the clinical signs. A I-V scale is used to stratify dogs with disc disease. Dogs with grade I disease exhibit only discomfort in the neck or back, Grade II-IV patients display a loss of neurologic function from fine motor control to complete loss of motor function. Grade V patients have lost the ability to transmit pain sensation from the appendages to the brain, a functional severing (transaction) of the cord.
Dogs suffering from stage I or II disease often respond to medical treatment consisting of anti-inflammatory medications, drugs for pain relief and strict (crate) rest. While dogs more severely affected can be treated medically most will regain function more quickly and regain a greater degree of function if veterinary surgical treatment is pursued. If medical treatment is elected, it is critical that the patient be monitored for any signs of progression as a Grade I or II dog can rapidly (within hours) progress to a grade V dog. The prognosis for dogs with Grade I-IV disease is very good with greater than 90% of patients regaining ambulatory abilities in 1-6 months time. The prognosis for dogs classified as grade V is guarded with less than 30% regaining ambulatory abilities.
- Breeds most commonly affected are long-backed, short legged dogs, such as the Dachshund, Shih-Tzu, Cocker Spaniel and Beagle breeds.
- Signs of IVDD in the lower back (thoracolumbar region) include:
- Reluctance to jump, walk or climb stairs
- Wobbly hind legs or hind legs cross while walking
- As condition worsens:
- Inability to walk or stand
- Inability to urinate
- Symptoms in the neck region include:
- Neck pain and will protect neck from movement
- Stiff gait or unwilling to lift or bend neck
- Sudden movements may produce a yelp
- Front or rear limb weakness
Depending on the location of disc injury or abnormality, the neurosurgery performed will be a Hemilaminectomy, Ventral Slot Decompression, or Dorsal Laminectomy.
The surgical procedure is designed to relieve pressure on the spinal column that causes pain and paralysis. The operation will generally begin immediately following a diagnostic CT Scan, or occasionally, a myelogram. All of the surgical procedures consist of removing the bony portion of two adjacent vertebra to allow access to the spinal canal. This enables the veterinary neurosurgeon to remove the herniated disc material that is compressing the spinal cord.
Clif the Beagle, one day after Hemilaminectomy Disc Surgery
Following corrective surgery, the amount of time it takes to regain function is highly variable. For some return of neurologic function is almost immediate. The majority of patients see a gradual return to function over 1-3 months, while in severely affected patients, improvement will continue for up to 6 months.
Approximately 90% of patients return to full function after disc surgery and ultimately live pain-free, healthy lives.