Intervertebral Disk Disease Update
By Thomas K. Graves, DVM, PhD, DACVIM - Chief of Small Animal Medicine, University of Illinois College of Veterinary Medicine
Last month I was lecturing at the American Animal Hospital Association convention in
I'm aware that there are many Peke breeders who swear that no Pekingese back should ever find itself beneath a surgeon's knife. I'm also aware that many veterinarians think every dog with disk disease needs surgery. Medicine is never black and white, and, in my opinion, neither position is correct. Let me review some of the background information originally published in the chapter on intervertebral disk disease from the PCF publication "Common Medical Disorders of the Pekingese."
Intervertebral disks are pads of cartilage located between the bones of the vertebral column. In Pekingese dogs, this cartilage commonly degenerates and loses its elasticity. When this occurs, the degenerate disk material can sometimes extrude from its normal position between the vertebrae and impinge on the spinal cord, the large bundle of nervous tissue that runs the length of the spinal canal. The extruded disk material presses against the spinal cord causing an array of clinical problems. The degree of severity of clinical signs depends on the degree of compression of the spinal cord and on the location of the extrusion. This is a degenerative disease in Pekingese dogs, and is not due to back injury. Many Pekingese owners believe that the use of stairs predisposes their dogs to intervertebral disk disease. Ramps are used commonly in order to prevent their dogs from using stairs. A true cause and effect relationship has been neither studied nor proven.
Clinical signs of intervertebral disk disease reflect the degree of compression of the spinal cord and associated nerve roots. In some mild cases, the only sign of a disk extrusion is back pain. This pain can sometimes be excruciating despite relatively mild spinal cord compression. In some cases, disk disease is mistaken for abdominal pain. The dog shows signs of pain when picked up, and splints the abdominal muscles in an attempt to prevent movement of the spinal column. In more severe cases, function of the legs is impaired due to spinal cord injury. If the disk extrusion is in the neck, all 4 legs can be affected. If the extrusion is further down the back, only the hind limbs are affected. The neurological signs include loss of coordination of the limbs, stiffness of the legs, exaggerated or diminished reflexes, and, in severe cases, complete paralysis.
Diagnosis begins with a complete medical history and physical examination. A complete neurological examination can not only identify the nature of the problem, but can also determine the approximate location of the disk extrusion. To document the presence of an extruded disk, radiographs of the spine are taken. It should be noted that plain radiographs of the spine often fail to identify the disease process. However, unless surgical treatment is planned, the radiographic demonstration of the lesion may not be necessary. Definitive identification of a disk extrusion requires other diagnostic imaging test, such as myelography (radiographs taken after injection of radiographic dye into the space around the spinal cord), magnetic resonance imaging (MRI), or computerized tomography (CT scan). These imaging techniques are not routinely performed at most veterinary practices.
Here is what I consider the most up-to-date information about treatment. Any experienced Peke breeder can tell you that most Pekes with disk disease do not need surgery, and I agree. With medical management and cage rest, most dogs will recover neurological function. Here's what we don't know. No published research that I am aware of has ever compared the outcome of cases managed with medication and cage rest compared to those managed surgically. For that reason I cannot tell you that surgery might not actually afford faster and more complete recovery. Because the answer to that question is not known, and because surgery is very costly, I recommend a conservative approach. We know that corticosteroids help if they are given within the first two (possibly up to three) days after a disk herniation. Wc also know that large doses of injectable methylprednisolone sodium succinate (Solu-MedroI) are most effective. Solu-Medrol is given at 30 mg/kg IV, and then repeated at half the dog a few hours later. If these injectable steroids are not available, it makes sense to use prednisone instead, and I have seen many Pekes treated successfully in this way. Long term treatment with steroids is probably not beneficial in terms of the clinical outcome, but sometimes they are used for the inflammation and swelling associated with a disk problem. Other anti-inflammatory drugs are probably better and safer (more on that later).
There are two instances in which I think surgery is indicated. The first is intractable severe pain. Some dogs, even with mild disk extrusions, are in excruciating pain. The pain may eventually subside, but the available analgesic drugs are not usually sufficient to control such severe pain, and it can persist for days and weeks. Surgical decompression of a disk can immediately relieve this pain, and I would certainly recommend surgery in this situation. It is humane.
The second instance in which J recommend surgery is acute and complete loss of deep pain. If a dog has absolutely no pain sensation or neurological function after a disk extrusion, the damage is very severe and the dog stands a very good chance of being permanently paralyzed if surgery is. not done as soon as possible. Again, no one has studied the outcome of medical management and cage rest vs surgery for dog with Ioss of deep pain. They have, however, studied what happens in dogs that have surgery within the first 48 hour of such a severe disk event vs. those that have surgery later than 48 hours after 10 of deep pain. In those comparisons there is a dramatically better outcome in dogs treated early. Most dogs treated later than 48 hours after the injury do not recover whereas most dogs that get surgery right away do. For that reason, it make little sense to me to avoid surgery in a Peke with loss of all pain sensation accompanying paralysis from a disk extrusion. Yes, I have seen Pekes recover eventually without surgery in this instance, but that is the exception to the rule.
Thankfully, most disk extrusion are not so severe, and most dogs will recover without surgery. Cage rest must be strict, and pain management is' an important component of treatment as well. Non-steroidal anti-inflammatory drug such as Rirnadyl, Zubrin, and others work well for this purpose. NSAIDS should not be used in combination with steroids because the combination can lead to gastrointestinal ulceration. J have seen dogs die from being on NSAID/steroid combinations, and I treat dog in our emergency room frequently for this problem. Chronic steroids alone can also cause gastric or intestinal ulceration, as can large dose of NSAIDs . The key to treatment is cage rest. J n my own dogs, I have probably seen 10 or so disk problems over that past 24 years. Only once have I had surgery done on one of my dogs, and that was because his pain was un controllable. Now, at the first sign of back pain -and that can be subtle because e people often think dog have abdominal pain when the pain is really originating in the back - my dogs get a ingle large dose of steroids and then they get crated. They are let out only briefly for necessary bathroom breaks. I recommend 4 week of cage res t.
There are some new treatments on the horizon. Recently, researchers have shown promising preliminary results using injectable polyethylene glycol or related polymers within the first day or two of a disk extrusion, Dogs have been shown to regain neurological function more fully and more rapidly with this treatment. Again, the comparisons have been with or without the drug in dogs undergoing surgery for severe disk disease. No one has evaluated the usefulnes of the treatment alone - i.e. not as an adjunct to surgery. I wish someone would do this research, and I should think that would be the kind of study the Pekingese Charitable Foundation would Iove to fund.
There are alternative treatments also being tried, but I am less familiar with these. Some people swear by acupuncture and chiropractic therapy for dogs with disk disease. There is no rigorous scientific proof that these treatment are useful, bur I think we should keep an open mind. I've heard of several "natural" remedies for disk disease - diets, anti-oxidants, herbal preparation, etc., and I have no experience with these treatments. In general, I am sceptical because naturopathic and "nutriceuticals " are usually,not subjected to the same rigorous safety and efficacy evaluation as are other kind of medical treatment , and I worry about the possibility of doing harm. I hope these treatments are adequately studied in the future so that safe recommendations can be made.