Intervertebral Disc Disease - Slipped Disc
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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

Discs in the mid back region (thoracolumbar) tend to be under the most stress thus rupture more commonly

The result is weakness, incoordination, and frequently paralysis

A hemilaminectomy is usually needed to remove ruptured disc material, which is compressing the spinal cord

If your pet has sensation in the hind limbs prior to and after surgery, there is a 90% chance that your pet will regain the ability to walk well again


Anatomy

  • The spine is made up of many bones called vertebrae. These are held together by ligaments, muscles, and intervertebral discs. The discs act as shock absorbers between the vertebrae.
  • An intervertebral disc consists of a fibrous outer ring and an inner part that is soft and jelly-like (imagine a jelly doughnut) called the nucleus pulposus. The fibrous outer ring is thinner at the top than the bottom.

 

Disc rupture

  • Discs in the mid back region (thoracolumbar) tend to be under the most stress thus rupture more commonly
  • When a disc becomes diseased, either through gradual degeneration or injury, the thinner top portion of the outer ring tears, and disc material displaces into the spinal canal located directly above the disc.
  • When the disc ruptures completely, the outer ring collapses and the inner jelly-like portion is forced into the spinal canal.
  • The spinal cord is located in the spinal canal. A bulging or ruptured disc causes irritation, pressure, or damage to the spinal cord. This causes inflammation which results in irritation, pressure, or damage to the spinal cord.
  • The resulting inflammation causes back pain, weakness, incoordination, and frequently paralysis. The damage to the spinal cord impairs the transmission of "messages" down the cables (neurons) in the spinal cord. Thus, loss of use of the limbs and little or no control of the bladder and sometimes the bowel occurs. When severe damage to the spinal cord is present, loss of pain sensation to the limbs occurs.
  • Below is a CT scan of a disc rupture in a dog - D is the oval shaped intervertebral disc; note the white part of the disc which is the diseased (calcified) nucleus pulposus; a fibrous ring surrounds the nucleus pulposus; also note the large amount of herniated white disc material labeled with an arrow that is compressing the spinal cord (yellow) against the top of the spinal canal

      

 

Diagnosis

  • A diagnosis of intervertebral disc disease is based on physical signs, neurological tests, and radiography.
  • In order to diagnose where the spinal cord is damaged, a myelogram usually is required. This procedure involves inserting a needle in the bag (dural sac) that surrounds the spinal cord and dye (which can be seen on radiographs) is then injected. Radiographs (x-rays) are made to see where the spinal cord is being compressed.
  • In most cases a CT scan is also made of the spine to clearly define the exact location of the disc material. When the surgeon has this information, less manipulation and trauma to the spinal cord may result during the surgery. A CT scan may not be needed if the myelogram provides a clear indication of the exact location of the herniated disc material.

 

Surgery

  • A hemilaminectomy is usually needed to remove ruptured disc material, which is compressing the spinal cord. During the surgery a hole or window is made on the side of the vertebrae at the site of the offending disc. The hemilaminectomy also relieves some pressure off of a swollen spinal cord.
  • If the mid-back is being operated, fenestration of intervertebral discs in the area is frequently performed. Fenestration involves making an incision in the side of the disc to allow the jelly portion to leak out. This decreases the risk of a future disc rupture and spinal cord compression in the future.

 

Prognosis

  • If your pet has sensation in the hind limbs prior to and after surgery, there is a 90% chance that your pet will regain the ability to walk well again. After surgery some pets will regain function quicker than others.
  • By 3 to 6 weeks after surgery most pets will be able to walk again. Sometimes no improvement in the neurological status is seen in the first month, then a rapid improvement occurs. Healing of the spinal cord will continue for a period of 6 months after surgery (at most 9 months). Therefore, by the time 6 to 9 months have lapsed, your pet’s neurological status will be as good as it is going to get.
  • Occasionally some pets will still have some residual weakness in the hind limbs, but will be able to ambulate well enough to be a functional pet.
  • Dogs that have no deep pain sensation to the hind limbs may never walk again. If surgery is done within 12 hours after sensation to the hind limbs is lost, there is about a 50 to 75% chance that the pet will walk again.
  • In the event that your pet does not regain the ability to walk again, a K-9 cart can be fitted to your pet. This device basically is a wheel chair for pets. It has a harness, which is strapped around the pet and wheels to allow the pet to ambulate with the front limbs.

 

Postoperative care

  • A urinary catheter is usually placed if your pet is paralyzed and has no voluntary motor function to the hind end so that the pet will be kept dry and clean.
  • Medications are given include:
    • Steroids: to help prevent swelling of the spinal cord and prevent free radical damage to the cord; if used at all they are only given at high doses during the first 24 hours.
      • Side effects of steroids:  Stomach ulcers, rupture of the colon due to ulceration, pancreatitis, increased thirst and urination, increased appetite
    • Pepcid and carafate and misoprostol
      • These are used to treat stomach ulcers if they occur
    • Antibiotics
      • These are given intravenously during surgery to prevent against infection.
      • Antibiotics may also be continued after surgery if a urinary catheter was used after surgery to minimize the possibility of a bladder or kidney infection.
    • Muscle relaxants (valium or methocarbamol)
      • If your pet has pain due to back spasms after surgery or if you have a difficult time expressing the bladder, a muscle relaxant may be prescribed.
  • Rest: Your pet should be kept in a crate at all times except for urination and bowel movements for a period of one month.
  • Passive rehabilitation: The joints of the hind limb (ankle, knee and hip) should be flexed and extended. Another important exercise is called abduction of the hip. This involves pulling the leg away and toward the belly. These exercises will keep the limbs from getting permanently stiff. This activity should be done 4 times daily for 10 minutes each time until your pet can walk again.
  • Active rehabilitation: Your pet’s back end should be elevated and the hind limbs placed in a standing position. As you balance your pet, allow standing. Early on after surgery your pet will be weak, but with time he/she should be able to support weight for a longer period of time. This exercise should be done 4 times daily for 5 minutes each time. Another form of rehabilitation therapy is swimming (if a water facility is available). This can be started about 7 days after surgery (at this time the incision will be sealed). Best is to use warm water. Swimming (with support under the belly) should be allowed 4 times daily for 10 minutes per time.
  • Bladder care: It is very common for patients with spinal injury to have lost control of the bladder and bowels. Your pet should be taken outside 4 to 5 times daily for elimination purposes, so that your pet will be encouraged to do this bodily function outside. If your pet is not urinating on his/her own, the bladder will need to be expressed (do this outdoors). This is done by applying constant pressure to the belly in front of the hind limbs. Your pet should have a bowel movement with in the next 3 days.
  • Incision: Please check the incision for signs of infection: redness, swelling, pain or discharge. Do not allow your pet to lick at the incision. Please make an appointment to return to MVS in 10 to 14 days from the time of surgery for evaluation of the incision (usually no external sutures to be removed) and neurological status.
  • If your pet is overweight, weight reduction is needed since excess weight puts additional strain on the back.
  • Provide a soft padded bed to prevent bedsores. These are sometimes seen on the points of the buttocks if the pet is constantly sitting up on its hind end. Any of the bony parts of the limbs can develop bed sores from laying on that part of the body too long and failing to turn the body.

 

Notify the doctor if any of the following occur

  • Your pet seems increasingly uncomfortable
  • Your pet loses control of its bowel movement, is constipated, or has bloody or dark stools
  • Your pet has difficulty urinating or you cannot express the bladder
  • Your pet has breathing problems, rigid front legs or seizures.

 

Intervertebral disc disease of the neck

  • Dogs having a disc problem in the neck frequently only have pain and sometimes lameness of one of the front limbs
  • Some dogs may have paralysis of all four limbs
  • The disc material is usually removed by making a hole in the bottom of the vertebra called a ventral slot
  • Many dogs will have immediate relief following neck surgery, but occasionally the neck pain may take 1 to 2 weeks to completely resolve

 

Potential complications

  • Infection of the spine
  • Bladder infection
  • Temporary worsening of the neurological status after surgery is not uncommon due to the myelogram and the surgical manipulation. If your pet can walk prior to surgery and cannot just after surgery, do not be alarmed. The most important factor that indicates whether your pet will recover again is retention of good sensation to the hind limbs after surgery.
  • Permanent paralysis can occur, but is unusual if deep pain sensation was intact prior to surgery
  • Anesthetic death
  • Life threatening pneumothorax or leakage of air in the chest following fenestration can occur but is rare.
  • Side effects due to medications (see above)

 

Dogs that do not regain function of hind limbs

  • Some dogs will not regain the ability to walk again following surgery in spite of our efforts; dogs that do not have deep pain sensation prior to surgery have a a poorer chance to regain function.
  • These pets do not need to be euthanized, but require extra attention which includes the following:
    • exercise
    • expressing urine from bladder
    • urine tests every 2 to 4 months to make sure that bladder infection is not present
    • A K-9 cart can be purchased from a company on-line to allow your pet to go for walks again (of course using the front limbs only).  In general, pets adjust to the use of a K-9 cart very quickly and enjoy their walks once again.  Below is a photo of a dog harnessed to his K-9 cart.

      

Frequently Asked Questions After Surgery

When should my dog have the first bowel movement after surgery?

  • Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
  • Reasons that a dog will not have regular bowel movements after surgery include:
    • The dog has been fasted prior to surgery
    • Dogs do not eat well during the hospital stay
    • They frequently do not eat well when they go home
    • They are fed highly digestible food that produces little stool
    • Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
  • If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
    • Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable

My pet had surgery and will not eat.  What can be done?

  • Dogs
    • Most pets will not eat their regular dog food after surgery, especially if it is kibble.
    • Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source.  The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked).   The carbohydrate can be pasta, potato or white rice.
    • Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
    • Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
    • Try Hill's A/D diet available at most veterinary hospitals
    • Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
    • Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
    • Remember that most pets will not eat the first day or two after they get home from surgery
  • Cats
    • Offer smelly foods that contain fish such as tuna or smelly cat foods
    • Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
    • Hand feeding:  with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
    • Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
    • Some cats will only eat dry food, try kibble if your cat normally has been fed that food
    • Petting and stroking your cat frequently will help to stimulate appetite
    • Remember that most pets will not eat the first day or two after they get home from surgery
    • Appetite stimulants such as cyproheptadine may be helpful
    • If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop

My pet is vomiting.  What can be done?

  • The first thing for you to discern is whether your pet is vomiting or regurgitating.  Both will result in fluid or food being brought up.  Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus.  Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled.  Usually the regurgited material will be clear or brown colored fluid. 
  • Next is to identify the cause of the vomiting or regurgitation.
  • Causes and treatment of vomiting after surgery
    • When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
    • Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery.  In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart.  Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to.  The antibiotic in some cases may be changed to a different one, or may be discontinued. 
    • Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days. 
    • An uncommon cause of vomiting after surgery is internal organ failure.  Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
    • If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present.  Do not ignore this sign.
    • Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days.  In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days.  Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats.  You should always consult a veterinary healthcare professional before administering medication.
  • Causes and treatment of regurgitation after surgery
    • The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia.  Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis.  This results in poor motility of the esophagus, therefore water and food will accumulate in this structure.  In most cases, esphagitis is self-eliminating and will resolve within two or three days. 
    • If the esophagitis is severe the esophagus may develop one or more strictures.  A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week.  This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope).  If an esophageal stricture is chronic surgery is needed.
    • Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other).  Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.

How do I know that my dog is in pain following surgery?

  • Signs of pain include
    • crying
    • biting if you get near the surgical site
    • grimacing (lips are pulled back and the the dog looks anxious)
    • tragic facial expression
    • panting
    • restlessness and unable to sleep; pacing
    • if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
    • the worst pain will be for the first 2 to 3 days after surgery

What can I do to control my dog's pain?

  • Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
  • Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
  • If an orthopedic surgery has been done cold packing the surgical site may be helpful
    • A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack.  An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern.  Cooling the surgical site helps to numb the area.

How do I know that my cat is in pain following surgery?

  • Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
  • Signs of pain in a cat include the following:
    • biting if you get near the surgical site
    • growling or deep cry
    • not wanting to eat
    • hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)

What can be done for pain at home for my cat?

  • Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
  • Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
  • Anti-inflammatories can be used, but the dose is much less than dogs

Is it okay for my pet to lick the incision?

  • If a dog licks the incision, the healing process may be delayed.
  • Licking can remove stitches and cause the incision to open
  • Licking can become a severe habit that is difficult to break
  • Licking can cause infection as the mouth has many bacteria
  • Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
  • To stop your pet from licking the following can be tried:
    • Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
    • Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
    • A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
    • A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
    • Bitter apple can be applied around the incision; many dogs will continue to lick  after application of this topical
    • Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
    • Antipsychotic medication in some cases is needed

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  • Experience in the development of new surgical treatments

  • Rigorous examination by the American College of Veterinary Surgeons to ensure competency in advanced surgical techniques

  • Assurance that a veterinarian is a surgical specialist

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