Intervertebral Disc Disease
The dog’s spinal column consists of the spinal cord that is protected by the vertebrae. The intervertebral discs are structures that lie between the individual vertebrae and act as a cushion between the discs. Each disc has a fibrous tissue outer layer called the annulus fibrosus that surrounds a soft inner core called the nucleus pulposus (similar to a jelly filled doughnut).
Intervertebral disc disease is a premature hardening of the center of the disc, and weakening of the outer layer of the disc that occurs in chondrodystrophic dogs such as dachshunds. As the outer layer of the disc ruptures, the inner material is displaced upwards against the spinal cord. This herniated disc material injures the spinal cord and results in cord swelling and compression. Consequentially, the nerves within the spinal cord traveling to the legs and urinary bladder become damaged. This in turn results in loss of limb function that can range from weakness to paralysis, and loss of bladder control.
In some cases, the damage to the spinal cord is minor, clinical signs are mild, and anti-inflammatory drugs such as methylprednisolone can be given to decrease the swelling in the cord and allow function to return. If methylprednisolone is given, the animal may feel better and may want to be active. However, it is extremely important that the dog is strictly confined to prevent further herniation of disc material. In about 4-6 weeks, the rupture heals and the dog can resume normal activity.
In other cases, the amount of disc material compressing the cord is too great and conservative therapy is unsuccessful. These dogs require surgery to remove a section of bone over the spinal cord (hemilaminectomy), and to remove the herniated disc material in order to relieve the pressure on the cord. Before surgery can be done, radiographs (x-rays) and a myelogram (a special x-ray in which dye is injected around the spinal cord) must be performed to identify the area of the spinal cord that is involved. After surgery, the prognosis is still guarded. Unless there has been severe damage to the cord, most dogs will regain some degree of neurologic function may and be able to walk.
Some dogs have such severe damage to the spinal cord that they can no longer feel when their toes are pinched and are said to be “deep pain negative.” In this group of dogs the prognosis for regaining use of the legs is very poor. These dogs can still receive decompressive surgery and if the cord appears intact, we can wait to see if the dog regains function. After 6 months, if the dog has not regained function it is highly unlikely that the dog will walk again.
Your dog will require a great deal of care until hind limb and bladder function are regained. Cage confinement is necessary to prevent injury. Soft dry bedding must be supplied to prevent bedsores from developing. The bladder may need to be expressed (manually squeezing on the abdomen to apply pressure to the bladder and cause urination) three to four times per day. Physical rehabilitation is important to maintain muscle tone and joint mobility.
Your dog has had a decompressive hemilaminectomy (the removal of bone over the area of spinal cord compression). Following surgery, your dog was observed for signs of discomfort or any complication associated with the surgical site, neurological function (pain sensation, reflexes, ability to voluntarily move the legs, and bladder function) has been evaluated several times per day and we are now comfortable with discharging your dog. The flowing guidelines will help with your dogs recovery.
1. Because your dog is paralyzed or uncoordinated, it could easily get hurt if allowed to roam free in the house especially around steps or stairs. We recommend you keep your dog confined to a cage, unless under your direct supervision. Soft dry bedding, at least one inch in thickness, must be supplied to prevent bedsores from developing. In addition, the bedding must be kept clean and dry to prevent urine scald. If your dog does come in contact with any urine, rinse the affected area with warm water and pat dry with a towel.
2. If your dog is unable to urinate, you will be shown how to express the bladder. This must be done three to four times daily to keep the bladder empty. Taking your dog outside and placing him/her in a standing position may help promote urination. If he/she does not produce any urine, or if you notice that the urine is discolored or foul smelling, please call the Purdue Small Animal Hospital or your veterinarian for advice.
3. If antibiotics have been prescribed for your animal, please continue to administer them until they are gone.
4. You may need to take your dog to your referring veterinarian in 7-10 days for removal of the skin staples. You will need to monitor the incision site for signs of infection such as pain, heat, swelling, redness, or discharge.
5. Please make an appointment to return to the Small Animal Clinic in 3 weeks, 6 weeks and again in 6 months following the surgery for reevaluation. Plan to come early for the 6 week and 6 month appointments as your dog will need to spend the whole day at the teaching hospital.
6. Physical Rehabilitation is very important to your dog’s recovery. Normally, physical rehabilitation includes passive range of motion, sitting and standing exercises, assisted walking (towel walking), and swimming. All these exercises will be explained and demonstrated to you when your dog is discharged.
7. If your dog shows worsening of neurologic status, such as breathing difficulties, or changes in movement in the front limbs, you should contact the veterinary teaching hospital immediately.