Laryngeal Paralysis (Paralyzed Voice Box)
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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

Laryngeal paralysis is a condition in which the muscles of the voice box are paralyzed, thus when a dog breathes in the voice box opening closes down and the dog can not inspire

Surgery is important to help with breathing and prevent a respiratory crisis during warm weather conditions

Prognosis is good with the surgery if the dog does not have any concurrent swallowing difficulties


Introduction - What is it?

  • The larynx is commonly known as the voice box. It contains the vocal cords, which allow vocalization in dogs and cats. The larynx is the first part of the airway that prevents anything but air from getting into the trachea (windpipe). In essence it is the gateway to the airways and lungs.
  • The front part of the larynx has a pair of doors which are the arytenoid cartilages. The doors open during inspiration (breathing in) by the pull of the cricoarytenoid dorsalis (CAD) muscle.
  • In order to examine the larynx your pet will be lightly anesthetized. As the pet breathes in and out the function of the larynx is evaluated.
  • Illustration below left of a normal larynx (voice box) - Take note of the CAD muscles (red striped structures) which pull on the arytenoid cartilages and open the airway (black slit).  The pale blue structures are the vocal cords; the epiglottis is a valve or flap that folds over the larynx during swallowing to prevent aspiration of food and water.
  • Illustration below right demonstrates laryngeal paralysis - When the CAD muscles are paralyzed, the arytenoid cartilages are not pulled back, which results in a narrowed airway (black slit).  When the pet tries to breathe in, the negative pressure from the windpipe will also pull the arytenoid cartilages together (red arrows), which even further compromises the airway.

  

Laryngeal tie-back surgery

  • A major contraindication against this surgery is swallowing difficulties or regurgitation as these dogs will get pneumonia after surgery.
  • In preparation for surgery, your pet will be anesthetized. The side of the neck (usually the left) is shaved. An incision is made on the side of the neck over the larynx.  Two nondissolving sutures are used to replace the left CAD muscle. The arytenoid cartilage is therefore "tied-back" in an open position.
  • Only one side of the larynx is tied open. If both sides of the larynx are tied open at the same time, the risk for pneumonia is increased.
  • Below is a an illustration of a larynx after tie-back surgery has been completed; the arrow represents the direction of pull of the suture that is placed to hold the arytenoid cartilage open.

      

After care and convalescence

  • After surgery has been completed intensive care must be provided for the best chance for a successful outcome. Intravenous fluids may be continued over night. Most patients having a routine tie-back surgery are discharged from the hospital the next day after surgery.
  • After your pet leaves the hospital pain is controlled with oral medication if needed.
  • Antibiotics may be prescribed to your pet if the surgeon feels that this is needed.
  • The feeding and water bowls should be elevated about 8 to 10 inches off of the floor. Canned food should be cut into chunks for the couple of weeks. Kibble could also be moistened with warm water before it is fed. Which ever food type seems to cause less coughing should be fed. Dry kibble should be avoided for the pet’s life.
  • Dusty environments should be avoided.
  • Swimming will no longer be permitted. If your pet’s head would go under water, the larynx would not be able to close and drowning could occur.
  • Exercise should be restricted for one month to prevent break down of the laryngeal tie-back.
  • A harness should be used instead of a collar, in order to take pressure off of the windpipe and the larynx.
  • Most pets do well following laryngeal tie-back surgery. Breathing is greatly improved and your pet should not get into a crisis again. Your pet likely will not be able to bark again or the bark will be hoarse. During heavy panting your pet could still have increased respiratory noise, as only one side of the larynx has been tied open and the other vocal cord may flutter as air moves in and out.

 

Potential complications

  • As with any surgery, complications may arise. Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oxymetry, inspiratory and expiratory carbon dioxide levels, and respiration rate), the risk of problems with anesthesia is minimal.
  • Infection is an unusual complication as strict sterile technique is used during the surgery and antibiotics are administered.
  • Seroma formation can also occur, as there may be an empty space between the tissues. This problem in general will resolve with time. Occasionally the seroma or fluid that has built up may require draining.
  • Pneumonia can occur after surgery because the airway is permanently kept open on one side.
  • Recurrence of laryngeal paralysis signs can occur if the cartilages (that are pulled open with sutures) are abnormally soft and do not hold the sutures well. In the event that this occurs, surgery can be done on the other side of the larynx.
  • Coughing is a expected following tie-back surgery on the larynx. Usually coughing is associated with drinking or eating. Within 6 weeks this usually improves, but occasional cough can occur.  If the cough becomes deep and productive, or your dog becomes depressed, you should alert us as pneumonia may be developing.

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

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