The spinal column begins at the base of the skull and ends at the tip of the tail creating the neck and backbone of the4 dog. The spinal column is formed by seven cervical, thirteen thoracic, seven lumbar, three sacral and usually five or more caudal (tail) vertebrae that are held together by ligaments and muscles. The vertebrae are each numbered for reference like C1-7, T1-13, L1-7, S1-3 and Cd1-5. This way problems can be localized along the spinal column as occurring at C5, T12, L7, etc. Each vertebra has a hole in the middle so as the vertebrae align with each other a channel call the spinal canal is formed and runs the entire length of the spinal column.
The spinal cord is a thick cable of nerves that begins at the base of the brain inside the skull and extends through the spinal canal. The relationship of the spinal cord and vertebrae are much like a string running through the beads of a necklace where the string is the spinal cord and the beads are the vertebrae. The spinal cord carries all the nerves going to and from the brain that make the legs and other structures function properly.
The intervertebral (IV) disc is a spongy cushion that is located between the vertebrae just below the spinal canal and spinal cord. The IV disc acts like a shock absorber and adds flexibility during movement of the spinal column. There are approximately 34 IV discs throughout the entire neck and back. Each IV disc consists of an outer tough ring that has a soft gelatinous center much like a day old jelly filled donut.IV disc disease is a degeneration of the disc that can occur due to premature or normal aging specific to certain breeds of dogs. A degenerating IV disc can rupture and spill its contents into the spinal canal (Type I disc herniation). This is often referred to as a slipped disc and can irritate, bruise or compress the spinal cord causing sudden pain or paralysis. A degenerating IV disc can also enlarge and slowly push up into the spinal canal (Type II disc disease) and put pressure on the spinal cord or nerve roots which enter and exit the spinal cord causing a slow progressive staggering gait, weakness in the legs or complete limb paralysis. Type I intervertebral disc herniation will be discussed here.
Type I intervertebral disc degeneration is common in many breeds of dogs at any age such as Dachshunds, Pekingese, Poodles, Maltese, Cocker Spaniels, Shi Tzus, Lhasa Apsos, Pugs and Beagles. The diagnosis is suspected based on the breed, history and clinical signs but tests such as spinal radiographs, cerebrospinal fluid analysis, myelogram and computerized axial Tomography or magnetic resonance imaging scans may be necessary to confirm the diagnosis.
If pain or mild limb weakness is the only sign then muscle relaxants, steroids and rest are prescribed for 2-4 weeks. The most difficult yet most important part of the treatment for mild IV disc disease is absolute rest. The medication may make them feel great and it is easy for dog owners to think their problems are over and this can lead to sudden paralysis. Rest often requires a major change in the family’s routine, as dogs must be confined to a crate or small room and not be able to play with their toys or other dogs. Further they must be taken briefly outside on a leash for urinations and defecations with no other exercise. Small dogs can be held and cuddled and carried, but no exercise.
Going up and down stairs, jumping on and off the bed or other furniture and sitting up to beg can cause the degenerating discs to rupture and paralysis can occur. Weight reduction may be necessary in obese dogs to reduce stress on the spinal column. With rest it is hoped that the degenerating IV disc will heal somewhat and the part that is extruded into the spinal canal will spread out and move away from the spinal cord relieving the pain or weakness without surgery. Many dogs with back pain will completely recover. They may have a recurrence of problems from the same or some other IV disc later in life. Dogs with neck pain usually have to have surgery as signs persist after rest and medications.
It is recommended that dogs that are at high risk for recurrence of IV disc disease be put on antioxidant drugs such as: Vitamin E 100-200 IU and Vitamin C 100-200 mg for a 10-30 lb dog. There has been some research done to show that antioxidants will protect the spinal cord to some degree in cases of injury. These vitamins can be found in any drug or health food store and a special dog formulation is not required. Going up and down stairs, jumping on and off the bed or other furniture, sitting up to beg, playing fetch or Frisbee and other games require sudden turns to the spinal cord or agility work should be avoided in the future to prevent recurrences. Sometimes no matter how well the weight and life-style are controlled other IV discs can cause problems.Acute explosion of a degenerative IV disc can cause sudden paralysis of the legs, which is a surgical emergency. A rapid acting steroid such as methylprednisolone sodium succinate or prednisolone sodium succinate should be administered intravenously as soon as possible after the onset of paralysis and then immediate referral to a specialist who performs decompressive surgery is essential. Treatment within the first 25 hours is the most crucial and after that time all treatments will be less effective. Approximately 80 percent of all dogs with acute paralysis given immediate rapid acting steroids and surgery within 24 hours are eventually able to walk again. Preventative surgery may be done to reduce the incidence of future problems at the same time.
After surgery most dogs need a rehabilitation time of 1-6 months but will continue to get stronger for 12 months. Most dogs cannot walk immediately even after surgery because the spinal cord has been bruised from the exploding disc. Most paraplegic dogs canoe urinate for several days. Usually they have to stay in the hospital to have their bladders manually emptied otherwise the bladder could be permanently damaged. Once they can urinate they are returned home as most dogs heal faster at home. At home simple physical therapy such as bending and moving the limbs through their normal range of movement and gentle massage will help keep limbs supple until the nerve function returns. Movement and massage in shallow warm water in the bathtub or sink can be great physical therapy, if the dog owner has the time. Fifteen minutes twice daily can be helpful. By using a sling made from a wide belt or towel they can be exercised with support. Some movement begins to return to the limbs within four weeks after surgery.
In cases of severe spinal cord injury, paralysis can be permanent. Some owners may elect to try a cart with wheels that supports the hind legs for exercise purposes. I suggest they try the cart for a month and see how they think their dog’s quality of life and how the household adjusts to a
paraplegic dog. Many dogs and families adjust fine. However dogs cannot live in the cart as they cannot lie down. The bladder must be emptied completely and urine samples monitored by a veterinarian for infections. Bladder infections, which then damage the kidneys is the most life threatening problem in paraplegic dogs. Most dogs with IV disc disease recover and with a few lifestyle changes lead happy lives.