Disc disease is a common problem in dogs. There are two major categories of disc disease, Type I and Type II. Type I disc disease is characterized by disc herniation (“slipped disc”) and a sudden onset of signs, Disc disease is seen most commonly in short-legged breeds (e.g., dachshund, basset hound, shih tzu, Lhasa apso, corgi, pekingese) It also occurs in larger breeds of dog, such as doberman pinschers.
Intervertebral discs deteriorate as part of the normal aging process. Some breeds of dogs such as dachshunds, may undergo disc degeneration earlier in life. Normal discs are made up of an outer fibrous ring and an inner gelatinous center. With age the disc changes and the outer ring often tears and the inner soft center of the disc hardens and may even calcify. A time may come when the torn outer ring may no longer be able to hold this hardened center in place and movement of the vertebrae may suddenly push the disc out of its normal position. This is called disc herniation. When disc material herniates, it may be pushed out the side, below, or up around the spinal cord.
The areas of the spine most commonly affected by herniated discs are the neck, and the mid-to lower back regions. Common signs seen with herniated disc are back pain, lameness, incoordination, and/or inability to walk in the hind legs, or all four limbs. Animals that are unable to walk may also be unable to urinate on their own. Although these signs indicate that the dog has a problem affecting the spinal cord, they do not indicate the specific area that is affected, or the cause of the problem. Tumor, fracture or infection involving the vertebrae or spinal cord may all produce neurological signs similar to a herniated disc. Further diagnostic tests are needed to determine the exact location and cause of the problem and to determine appropriate therapy.
In order to determine the exact location and cause of the problem, the animal must first be examined. The results of the neurological examination help veterinarian to determine which part of the spinal cord has been affected. General anesthesia is needed for further testing. Prior to anesthesia blood and urine tests are done to make sure that the dog is otherwise healthy and has no other problems that may increase the risk of anesthesia. Once these tests have been completed the patient is anesthetized for MRI of affected part of spinal cord.
Most animals with disc disease need surgery to remove the disc material compressing the spinal cord. Sometimes an animal with disc disease does not undergo surgery, but instead is treated with strict rest, which is accomplished by means of confinement to a cage. In general, this approach is used for a first attack of back pain and in animals that do not have problems walking. Strict cage rest does not relieve spinal cord compression, but it may help to reduce some of the pain and swelling around the spinal cord, and give the torn outer rim of the disc time to heal. It is not uncommon for animals treated this way to suffer repeated attacks of pain, lameness and paralysis, as often more disc material herniates and places additional pressure on the spinal cord.
Most animals with disc herniations of the mid back undergo a special type of laminectomy, called a hemilaminectomy, whereby only one side of the vertebrae is removed. In conjunction with the laminectomy, most animals also undergo fenestration of the discs in front of and behind the one that has herniated. In order to fenestrate a disc a small window is made into the outer fibrous ring of the disc, and the material in the center of the disc is removed. Fenestration is done to reduce the possibility of the surrounding discs from herniating and causing the animal problems in the future.
The speed of recovery from surgery and the extent of recovery of normal function (e.g., walking) is dependent on many factors, including how fast the disc material hit the spinal cord, the degree of the damage sustained by the spinal cord and the length of time that the spinal cord has been compressed by the disc material. Fortunately the majority of animals with disc disease that undergo surgery recover function to their limbs relatively quickly and completely.
At Serra Veterinary Hospital Inc. animals are usually hospitalized for about 3-5 days after surgery. They are generally discharged from the hospital once they are comfortable and are able to urinate on their own. Once home, the patient’s activity is restricted for 4-6 weeks. Skin sutures are generally removed 14 days after surgery. Patients are generally rechecked 4-6 weeks after surgery to assess recovery or earlier if any problems or concerns develop.
While most animals requiring surgery for one disc herniation do not suffer additional disc herniations, a small number of animals do. Therefore, it is very important that as many predisposing environmental factors be controlled as is possible. Owners are encouraged to institute weight control management to prevent obesity, start non-concussive exercise to promote fitness, eliminate stair climbing and to stop jumping behavior once recovery from the disc herniation has occurred.