Brachycephalic Airway Syndrome


Key Points

Breathing difficulty in a brachycephalic breed of dog or cat is commonly due to

  • stenotic nares
  • elongated soft palate
  • everted lateral ventricles of the larynx

The best prognosis following surgery is in pets that are immature

 

Anatomy

Air is passed from the nares (nostrils), through the nasal cavity and back of the throat, and into the trachea via the larynx.

Definitions:

  1. Nares = nostrils
  2. Nasal cavity = the nose cavity
  3. Turbinates = scroll like bones in the nasal cavity that are lined with mucosa which serve to warm and moisten inhaled air
  4. Mucosa = the skin like tissue that lines the inside of the nose (like the gums that line the mouth)
  5. Trachea = windpipe
  6. Larynx = voice box
  7. nasopharynx = airway passage that connects the nasal cavity to the back of the throat called the pharynx
  8. Lateral ventricles = cavities that are located adjacent to the opening of the voice box
  9. Hard palate = roof of the mouth (hard portion) that separates the mouth cavity from the nasal cavity
  10. Soft palate = a soft tissue structure extending from back of the hard palate which separates the back of the throat (pharynx) from the nasopharynx

 

What is brachycephalic airway syndrome?

This condition is due to compaction of the upper airway during development which distorts the normal anatomy. The result is that structures that normally fit well within the head and neck are disproportionate, thus the airway is not as open as it ought to be. The soft palate is frequently elongated in brachycephalic breeds (bulldog, Boston terrier, Shar pei, Pug, Himalayan cats, etc) and frequently will occlude the opening of the larynx. In addition, the nares commonly are smaller than normal in such breeds. Secondarily, the lateral ventricles which are normally concave pockets along side of the larynx become everted to form balloon-like structures which further occlude the opening of the larynx. The larynx may also become weakened with time and collapses together, which will further reduces the flow of air from the nose to the trachea. Another anatomical abnormality is an abnormally narrow windpipe called a hypoplastic trachea.

Weight gain is common in affected animals due to sleep apnea in brachycephalic breeds. This condition puts the pet in a state of low metabolism due to oxygen depravation. Fat accumulates in the back of the throat which further impairs the breathing.

 

Signs

Warning signs of brachycephalic airway syndrome include snoring when sleeping, snorting noises when breathing, collapsing when playing, and a purple color of the tongue. Signs are worsen with heat, exercise, and excitement. Other secondary signs may include vomiting which is due to stimulation of the receptors in the back of the throat. Aspiration pneumonia may also be present with this condition, and signs may include coughing, fever, lethargy, and inappetance.

 

Diagnostic testing

Standard testing prior to surgery should include chest radiographs to rule out heart disease and conditions of the lungs such as pneumonia. A side view x-ray of the neck is helpful to check for a hypoplastic trachea. Blood testing including a complete blood count, chemistry panel, and urinalysis should be done to rule out other conditions that may complicate surgery. An examination of the back of the throat is performed under general anesthesia. I generally perform this examination at the time of the proposed surgery.

 

Preparation for surgery

The pet should be fasted prior to surgery, as instructed by the surgical team. Water is usually permitted up to the time of admission to the hospital. The surgical team should be informed of any medications that your pet is currently receiving. Just prior to surgery, your pet will receive a sedative, have an intravenous catheter placed for the administration of intravenous fluids and intravenous medications, be induced under general anesthesia with medication(s), and have a breathing tube (endotracheal tube) placed to allow delivery of oxygen and gaseous anesthesia. While under general anesthesia, the pet’s breathing will be assisted with a ventilator and vital parameters such as heart rate, respiratory rate, core body temperature, blood pressure, oxygenation of the blood (pulse oximetry), exhaled carbon dioxide (capnography), and heart rhythm (EKG) will be monitored to ensure the pet’s well being. Pain will be controlled both during and after surgery with analgesics (pain-controlling medication). Please note that each surgical and anesthesia team may elect to chose a different, but effective analgesia protocol.

 

Surgery

Nares are surgically opened if they are stenotic. This generally necessitates removal of a wedge of tissue from the sides of each nare. In addition, I feel that it is important to also remove tissue extending deep to the nares to fully open the nasal passage. The photo right shows a severe case of stenotic nares that is surgically corrected.

 

 

The soft palate can be shortened using a number of potential methods. The traditional method involves simply cutting the tip of the soft palate off and over sewing the edges of the palate. The second method is cutting the tip of the palate off with a laser and the third method is performed using a specialized cautery unit called the ligasure. Swelling of the palate can occur with any of these methods of treatment. It seem that the older the dog, the greater the risk for having breathing difficulty after surgery. Without intervention after surgery, breathing difficulties can result in death of the patient. In fact, one surgeon whom I have highly respect (DJ Krawinkle), indicated that 50% of the mature bulldogs will have swelling postoperatively that requires intervention. In some cases, a tracheostomy is needed after surgery, but this significantly increases patient morbidity and hospital stay. Another study demonstrated that placement of nasotracheal catheters at the time of surgery to deliver oxygen, eliminated the need for tracheostomy in the postop period following soft palate surgery.

Finally, the everted saccules, if present are removed. This is a relatively fast procedure and only involves grasping and snipping this tissue off with scissors.

 

Care after surgery

Most pets having this type of surgery will stay in the hospital at least over night to monitor the pet for breathing difficulties. While in the hospital, intravenous fluid therapy likely will continue until the pet goes home. Oxygen therapy may be needed via a nasotracheal catheter. If severe breathing difficulties are present after surgery due to swelling and the oxygen therapy via the nasotracheal catheter is inadequate, a tracheostomy may be required. This necessitates making an incision over the neck and creating a hole in the trachea, through which a breathing tube (trach tube) is placed. This tube will need to be replaced every 6 to 8 hours and the tracheostomy site cleansed on a regular basis. This type of care should only be done in the hospital by an experienced team, as occlusion of the tube with mucus can create a life-threatening situation.

At home, medication to control pain after surgery should be administered for a few days. Antibiotics are commonly prescribed, but only may be needed for a week or two, unless the pet has pneumonia. If prescribed by the surgeon, cortisone may be needed for only a very short period of time after surgery. Exercise should be restricted for two weeks, but leash walks are generally permitted. A follow-up examination should be done in 2 weeks after surgery to evaluate the healing process.

 

Results

Most immature dogs that have surgical correction of the problem usually recover uneventfully. As a dog ages with untreated brachycephalic airway syndrome, secondary changes such as laryngeal collapse may complicate the recovery and worsen the prognosis. Aspiration pneumonia will complicate the recovery and in some cases can be fatal. A successful surgery will result in much better breathing, snoring will be reduced, exercise tolerance is greatly improved, sleeping will be much better, and weight loss with an appropriate dietary restrictions can be achieved. Although surgery can be successful, it is imperative that weight gain is not occur, as this will result in breathing difficulties again.

A complication that is seen following laser surgery on the nose in very small animals such as a cats is permanent structuring (narrowing) of the nares. This is caused by collateral damage to neighboring tissues. Below is a cat that has stenotic nares prior to laser surgery and then the disaster that followed. Take note that the photo below right shows that the nostrils have healed closed and the nose is gone, as a result of failed laser surgery. As a warning, only select a surgeon that has good experience with this technique. Be aware that the cold scalpel blade is unlikely to have this kind of end result versus when treated with laser.

Another potential complication of soft palate surgery is resecting the soft palate too short, which results in reflux of food into the nasal cavity with subsequent chronic nasal infection.


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