Brachycephalic Obstructive Airway Syndrome

Dogs with BOAS may have noisy breathing or snore, and some dogs may have reduced exercise intolerance or a cough. Exercise intolerance worsens in hot, humid weather. Many dogs have reflux signs such as bringing up white or yellow tinged foam. Some of the signs may be subtle like waking up at night, swallowing a bit, and then falling back asleep (silent reflux). Being overweight tends to worsen these problems.

Stenotic nares can be easily diagnosed on physical examination however definitive diagnosis of the other aspects of BOAS requires visual assessment under anaesthesia.

• Stenotic nares: This is a fancy name for narrowed nostrils, which reduces the volume of air that can flow through the nose. The sides of the nostrils may be sucked inwards when the dog breathes in, which totally occludes the nostrils.
• Elongated Soft Palate: It is difficult to fit the soft tissues of the canine mouth and throat in to the brachycephalic dog’s short face. As a result, the soft palate, which separates the nasal passage from the oral cavity, extends down into the throat partially obstructing the airway. Virtually all brachycephalic suffer from this. A dog with an elongated soft palate may gag, cough, retch or snore, particularly when breathing in.
• Everted Laryngeal Saccules: is a condition in which tissue within the airway, just in front of the vocal cords, is pulled into the trachea (windpipe) and partially obstructs airflow. Some dogs with BOAS will also have a narrow trachea, collapse of the larynx (the cartilages that open and close the upper airway), or paralysis of the laryngeal cartilages.
• Enlarged tonsils (Tonsillar hyperplasia): the tonsils are often enlarged due to chronic  inflammation. They further add to the excess tissue surrounding the airways. Removing the tonsils if they are enlarged improves outcomes for dogs undergoing this surgery.
• Tracheal Hypoplasia: where the trachea (windpipe) is too small. This condition cannot be treated however addressing the other airway issues may be of benefit.
• Overgrowth of the nasal turbinate bones: this occurs in some cases and may require additional surgery if breathing is not improved by correction of the above problems. Nasal CT is required before surgery and is performed at specialist hospitals.

Concurrent digestive diseases are common in brachycephalic dogs. They are prone to inflammatory gastrointestinal diseases (including Gastro-oesophageal reflux, sliding hiatial hernia). Addressing the airway disease first can help improve some of the gastrointestinal signs, however treatment of these issues are sometimes needed as well. Untreated gastrointestinal reflux can worsen airway disease and increase the risk of aspiration pneumonia (inhaling gastric contents and causing severe lung infection).

If BOAS is left untreated, secondary complications can occur and lead to Laryngeal collapse: This is more end stage disease, in which the cartilage frame of the larynx collapses into the middle, almost blocking the airway. It may lead to life-threatening respiratory distress. Surgical management of this condition is very difficult, and patients may require permanent tracheostomy (a hole in the throat for breathing). This is needed in less than 1% of cases.

In our experience over many years of treating these dogs over 95% of the animals we see significantly benefit from surgery. They are more comfortable following surgery, breathe more easily and are more active improving their quality of life.

The aims of surgical correction is to ease their breathing and reduce the secondary laryngeal changes.

The improvement in respiratory function is good to excellent in 85-95% of dogs who have early intervention with surgical correction. However, while we can improve their respiratory function, there are some aspects we cannot change with surgery and some dogs will still have clinical signs that may worsen over time.

A pre-operative chest x-ray is taken to make sure there are no signs of aspiration pneumonia (lung infection) prior to anaesthesia.

1. Widening of the nostrils: stenotic nares are corrected by removing a wedge of tissue from each nostril. They have a few dissolvable stitches, which do not need to be removed.  A newer procedure is available now which removes more of the nasal passage tissue (vestibulotomy) and the edges (wings) of the nostril are removed allowing even more airflow through the nostrils. This procedure involves no sutures so there will be some nasal discharge for the first two weeks. The edge heals and initially looks slightly pink, which eventually changes back to the normal colour of the nose (black).
2. The elongated soft palate is surgically trimmed, thinned, and sutured with dissolvable sutures.
3. Larngeal saccules: are trimmed, so they no longer sit in the airway blocking it.

All patients must be monitored very closely immediately after surgery. Significant inflammation or bleeding can obstruct the airway, making breathing difficult or impossible. Occasionally a tube must be placed and maintained through an incision in the neck into the trachea (temporary tracheostomy) until the swelling in the throat subsides enough that the pet can breathe normally. The risk of complications is increased if the surgery is done after 1-2 years of age, when there are secondary changes present, in particular laryngeal collapse.

Patients are usually observed in the hospital for at least 24-36 hours. Post-operative coughing and gagging are common.

The prognosis is good for young animals. They generally will breathe much easier and with significantly reduced respiratory distress. Their activity level can markedly improve. Older animals may have a less favourable prognosis, especially if the process of laryngeal collapse has already started. If laryngeal collapse is advanced, the prognosis is poor.

Patients are transferred to the Northside Emergency Vet Service for overnight monitoring as a precaution, and are returned to Allambie Vet the following morning. Patients are often discharged from our hospital that day.

In a small number of cases if significant post-operative inflammation occurs, our initial approach is to re-anaesthetise the patient and pack the pharynx with swabs soaked in hyper osmotic solution to help reduce the swelling, this resolves the issue in most cases. Occasionally (around 5% of cases), if the swelling does not resolve, a tube must be placed and maintained through a small incision in the neck into the trachea (temporary tracheostomy) until the swelling in the pharynx subsides enough that the patient can breathe normally. This can take 2-3 days. This happens in a small number of cases- and is typically related to the severity of the condition- but does add significantly to the care required for the patient and there will be additional costs for placing the tube and care at the afterhours center.

Regurgitation is common in dogs with brachycephalic airway disease and can complicate recovery from airway surgery by increasing inflammation in the airway and can lead to aspiration pneumonia (severe lung infection requiring hospitalisation until better).

We take precautions to reduce the risk of this happening with pre- operative antacid medications, anxiety relief medications (if needed), special care during anaesthesia and recovery.

A consult prior to surgery is recommended so the veterinarian can assess the overall health of your dog, address any reflux issues, go through the procedure, and give an estimate prior to booking the surgery.

Patients being booked in for airway surgery need to start an antacid medication 3 days prior to surgery. This medication helps reduce acidity if reflux occurs. Most French bulldogs will have reflux post surgery.

Our veterinarians Dr Jane, Dr Linda and Dr Kate currently perform Brachycephalic Airway Surgery. These surgeries are scheduled for Mondays, Tuesdays or Thursdays.

If you have any questions regarding Brachycephalic Obstructive Airway Syndrome, please do not hastate to contact Allambie Vet on 9905 0505.