Brachycephalic obstructive airway syndrome (or BOAS) is a condition affecting some dogs which makes it difficult to breathe due to the shape of their nose, head, and airways. This disease most commonly affects dogs known as brachycephalic breeds, such as English bulldogs, French Bulldogs, Pugs, Boston Terriers and Pekingese. These breeds have been bred to have short noses, and this results in the upper airways being compressed, obstructing the airflow in the upper airways.
Dogs with BOAS often have a history of loud breathing, snoring and poor exercise tolerance. These signs often worsen with hot or humid weather. Vomiting or gagging when swallowing may also be seen. During periods of excitement or stress, dogs may also turn blue in the tongue or gums, and possibly even collapse due to a lack of oxygen. These symptoms often vary between dogs, but as dogs age, the disease often progresses, and the clinical signs worsen.
Several contributing factors may be associated with this condition and include:
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Stenotic nares – Narrow nostrils which reduces the flow of air into the airways, which makes breathing difficult.
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Elongated soft palpate – The soft palate at the back of the mouth may be excessively long and may sit within the opening of the trachea (windpipe). This creates turbulent air flow and obstructs the airway, resulting in increased respiratory noise, and snoring.
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Tracheal hypoplasia – the trachea (windpipe) may be narrow or weakened. This condition cannot be treated, however addressing the other issues can help to manage this condition.
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Enlargement of the tonsils – the tonsils in the throat may be enlarged due to chronic inflammation.
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Everted laryngeal saccules – Increased effort during breathing may result in swelling to portions of the larynx. This swelling further increases resistance within the airways.
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Overgrowth of the nasal turbinates – the folds within the nasal cavity may be overgrown, resulting in further narrowing of the airways within the nose. This is difficult to assess and requires a CT scan to diagnose.
BOAS can be diagnosed during a routine examination of dogs. Stenotic nares are simply diagnosed during this examination. To further assess the airways and determine which other changes may be playing a role in this condition, further diagnostics are needed. Examination of the mouth and throat would require a general anaesthesia. This can be performed in animals of any age, and is often performed during desexing. Once the airways have been assessed surgery may be performed at this time or may be scheduled for a later date.
The most common corrective procedures involve addressing the stenotic (narrow) nares and elongated soft palate. In dogs with more advance condition, the everted saccules and enlarged tonsils may also be corrected.
Correction of the narrow nostrils is a low-risk surgery which adds a great benefit. We utilise multiple techniques to open the airways including an alarvestibuloplasty or a wedge resection. Slight bleeding may be normal following this procedure, otherwise there are minimal complications associated with this procedure. Opening the nose allows for a significant improvement in breathing and an excellent cosmetic outcome.
The elongated soft palate is treated by removal of the excessive tissue at the back of the throat. The soft palate is thinned and shortened to significantyl reduce the excessive soft tissue at the back of the throat. Once removed, dissolvable sutures are placed to allow the soft palate to heal. Complications with this procedure are not common, but if they occur can be serious. Through the use of stress-free handling, careful and experienced surgical techniques, and appropriate medications, the chances of these are minimised. Post-operative swelling is a possible complication which, if left untreated, could result in narrowing of the airway, making breathing difficult or impossible. This is a life-threatening complication and may require a temporary tube to be placed in the dog’s airways to allow them to breathe. In this situation, the dog may need to be transferred to an emergency centre for 24-hour monitoring while the swelling subsides. This complication is not common and is less likely to occur in younger animals who have not been suffering from the condition for a long time.
Once this brachycephalic surgery has been performed, the prognosis is good for young animals. They generally breathe much more easily and with a significant reduction in respiratory distress. In older dogs, the long-term prognosis will vary depending on the amount of swelling and laryngeal collapse present.
