Disc herniation can cause varying degrees of disability from back pain to paralysis

If your pet is acutely paralyzed, emergency surgery may be indicated

Our surgeons and neurologists have a 95% success rate with surgical treatment of disc herniations

Our doctors are available 24 hours daily, seven days a week, to treat any surgical condition of the spine, including treatment of disc herniation

What is it?

• Many terms are synonymous with intervertebral disc disease (IVDD) and include the following:
  • slipped disc - really a misnomer as the disc does not slip out of place
  • herniated disc or disc herniation
  • crick in the back
  • intervertebral disc syndrome (IVDS)
• Intervertebral disc disease is a condition in which a disc in the back (frequently the mid back) degenerates, the outer fibrous ring of the disc tears and the inner gelatinous substance displaces upwards into the spinal canal and compresses the spinal cord (see illustration right)

Anatomy

• See illustrations of spine (above and right)
• The spine in a dog is made of more than 30 bones. The neck bones are called the cervical vertebrae, the chest back bones are called the thoracic vertebrae, the mid to lower back bones are called the lumbar vertebrae and the three fused bones which are attached to the pelvis is the sacrum. A final set of spinal bones that we should mention are the tail bones also known as the coccygeal vertebrae.
• Between most of the bones of the spine is a disc (intervertebral disc) which acts as a shock absorber.
• Each disc has two components: the outer part of the disc is made of very strong fibrous material (called the annulus fibrosis) which holds the inner gelatinous material of the disc (called the nucleus pulposus) in place.

Clinical signs

• Breeds: both small and large breeds, but small breeds are more commonly affected
  • Dachshund
  • Lhasa apso
  • Poodle
  • Cocker spaniel
  • Shitzu
• Age: usually mid age, but young dogs are also affected
• Sex: no sex predilection
• Signs
  • Crying out in pain
  • If still able to walk - unwillingness to climb stairs, or jump on a elevated surface like a couch or bed
  • Hindlimb weakness
  • Knuckling of the paws
  • Wobbly gait - looks drunk
  • Paralysis of the hind limbs
  • Loss of bladder or bowel control

Diagnosis

• A diagnosis of intervertebral disc disease is based on physical signs, neurological tests, and diagnostic imaging tests such as a myelogram, CT scan or MRI.
• Myelogram: dye is injected into the fluid space surrounding the spinal cord, then radiographs (x-rays) are made to see where the spinal cord is compressed. Take note of the compression of the spinal cord (arrow) on the myelogram (photo right); the two small yellow arrows show the dye outlining the unaffected region of the spinal cord.
• CT-myelogram: dye is injected into the fluid space around the spinal cord and a special type of cross-sectional x-ray is made called a CT scan. This test allows the surgeon to identify the extend of the herniated disc better than a regular myelogram
• MRI: no injections into the spine are required. Cross-sectional and sagittal images are obtained from this scan. An MRI is the ideal test used to identify a nerve sheath tumor that is outside of the spinal canal.

Treatment

• Conservative therapy can result in resolution of clinical signs, however, if the pet does regain the ability to walk again, usually the function is not as good as it would be if surgery was performed.
• Surgery is frequently the best treatment.
• A surgical procedure called a hemilaminectomy involves removing a portion of bone from one side of the back bones at the level of the herniated disc (see illustration right). After the spine has been opened, the herniated disc material is removed from beneath the spinal cord.
• A procedure called fenestration may also be done to help prevent a future disc rupture. This involves opening the side of adjacent discs and removing the gelatinous nucleus pulposus material. One study reported a 4.4% recurrence rate when fenestration procedure was done versus a 6.6% recurrence rate when no fenestration was done. Our surgeons and neurologists advocate the fenestration procedure.

Potential complications

• Anesthetic death is a very uncommon complication under the care of our trained specialists.
• Infection of the spine, although possible, is very uncommon.
• Bladder infection may result from inadequate emptying of the bladder due to neurological dysfunction. Antibiotics are needed to correct this problem.
• Permanent paralysis can occur, but is uncommon
• Unresolving pain may be due to prolapsed disc material that is still irritating a nerve root. The clinical signs may ameliorate with time, however, in some cases additional testing and additional surgery may be needed.
• Side effects due to medications may include vomiting, diarrhea and loss of appetite. If any of these clinical signs occur notify the doctor who has performed the surgery on your pet.
• Leakage of air into the chest, which can be life-threatening, may occur if the thoracic vertebrae are being operated and the surgeon penetrates the chest cavity.

Postoperative care

• Medications that you may need to administer to your pet may include:
  • Steroids: help reduce swelling and inflammation
  • Muscle relaxants: help to minimize painful muscle spasms
  • Analgesics: a variety of medications are available for this purpose
• Rest: Your pet should be kept in a crate at all times except for urination and bowel movements for a period of one month.
• Rehabilitation therapy is very important of patients that are weak or paralyzed.
  • Passive rehabilitation: flex and extend the joints of the hindlimbs. These exercises should be done three to four times daily, 20 minutes per session.
  • Active rehabilitation: assist your pet in a standing position. When your pet gets tired and lies down, allow a short period of rest (30 seconds) and then get him/her back into a standing position.
• Bladder care is needed in most dogs that have had surgery for a thoracolumbar spinal cord lesion. If your pet is paralyzed, bladder control also may be lost. You may need to express the bladder so that it does not become too distended. Once the pet regains voluntary motor function of the hindlimbs, the bladder function usually has recovered.
• Check the incision for signs of infection: redness, swelling, pain or discharge. Do not allow your pet to scratch or rub the incision. If needed the neck may need to be bandaged until the incision has healed.
• A soft padded bed is essential during the recovery phase to prevent the development of bed sores/ulcers. If your pet cannot turn him/herself you will need to turn him/her from side to side every four hours.
• An evaluation of your pet will be made about 2 weeks after surgery at our hospital by a surgeon or neurologist.

Prognosis

• Following spinal surgery, it is common that the neurological status may be the same or somewhat worse than prior to surgery. This is caused by the myelogram and surgical manipulation of the spinal cord. In most cases this is a temporary set back and improves in a few days. Dogs that are paralyzed prior to surgery usually have a 3 to 6 week convalescent period before they can walk again. At this point they frequently are still unsteady on their hindlimbs. By 2 months after surgery most dogs are able to ambulate very well. Improvement in the strength of the hindlimbs can progress until the 6th to 9th month after surgery. In general about 95% of the dogs that have hemilaminectomy surgery will be able to walk again.
• Dogs that have had one disc herniation event are at greater risk than ordinary dogs for a repeat event.