Intervertebral disk disease (IVDD) is a common cause of neurological dysfunction or spinal pain in dogs and occasionally causes similar problems in cats. Intervertebral disks are located between the bones of the spine serving as shock absorbers and allowing for normal bending of the spine. As animals get older, the intervertebral disks gradually degenerate and in certain breeds of dog this process occurs early age. Degeneration involves loss of water within the jelly-like center (nucleus pulposus) of the disk. As the center of the disk dehydrates, it loses much of its ability to absorb shock and cushion the spine. When the spine compresses a degenerated disk, the force is transferred to the outer ring of the disk (annulus fibrosus) and this force eventually causes small tears to occur in the outside of the disk.
If the outer disk fully ruptures then dehydrated material from the center is expelled into the spinal canal causing compression of the spinal cord or nerve roots. If only the inner fibers tear then the disk will partially collapse causing bulging or protrusion. Pain, weakness or even paralysis may occur depending on the degree of compression or damage to the spinal cord with disk protrusion or rupture. Neurologic symptoms result from mechanical compression of the spinal cord, bleeding, compromise to the cord’s blood supply or metabolic injury inside the cord. A Board-Certified Veterinarian is the best diagnosis and treatment option for your pet with a spinal problem.
IVDD may occur anywhere in the canine or feline spinal column; however certain sites are more commonly affected than others. The most common locations are in the lower neck, the middle of the back and the lower back. Depending on the age and breed of your pet, certain sites are more likely to be affected than others. Other factors that increase the risk of disk disease include genetic predisposition, excessive weight, and lack of muscular fitness. Major trauma may cause rupture of deteriorated or even normal disks in any patient. The most affected breeds include Dachshunds, Beagles, Cocker Spaniels, Pekingese dogs, French Bulldogs, Basset hounds, Welsh Corgis, and toy/miniature Poodles. Most small dogs will generally experience a sudden onset of back pain which may then progresses to hindlimb weakness or paralysis. Some forms of disk disease are slow and deteriorate more gradually; signs are variable from back/neck pain to a wobbly gait, and this is typically observed in large breeds such as the German Shepherd, Labrador Retriever, Doberman Pinscher, and Rottweiler.
If the disk ruptures to the side or below, the result may only be mild pain lasting for a few hours to a few days. Such pain may even go unnoticed. If the disk ruptures upward, the degenerate nucleus is extruded into the spinal canal which has a profound impact on the spinal cord. This type of rupture results in severe pain and varying degrees of paralysis. The majority of dogs with a disk problem have spinal pain as their initial clinical sign. Other patients may have nonspecific symptoms such as loss of appetite, panting, decreased activity or being quieter than usual. Back pain may cause the dog to arch their back and guard their belly which may be misinterpreted as an abdominal problem. Disk rupture in the neck may cause the pet to have a stiff neck and they may not be willing to bend the head down to drink water or eat food. Rupture of a disk in the back commonly causes the pet to walk more slowly than normal, become unwilling to climb stairs, or be unwilling to jump on or off elevated surfaces. With more severe injury to the spinal cord, the patient may have weakness, knuckling of the paws when walking, a wobbly/unsteady gait, paralysis of the hind limbs and loss of bladder or bowel control. If your pet is showing signs of spinal weakness or pain, contact an ExpertVet certified facility immediately.
In order to properly diagnose IVDD, your Board-Certified Veterinarian will conduct a neurologic examination. Depending on the severity of the case and the overall condition of the affected animal, treatment may involve medication and/or surgery. Many dogs with disk rupture recover mobility but in very severe cases, the paralysis may be permanent even with surgery. Loss of sensation to the hindlimbs, often called “deep pain perception,” is associated with a poor prognosis for recovery since this indicates complete disruption of the spinal cord. Even if a dog is paralyzed, most of these patients will recover mobility with surgery as long as they have sensation to the hindlimbs. The prognosis for recovery if there is no sensation to the hindlimbs is, on average, 50% with surgery and time is of the essence.