Brachycephalic Obstructive Airway Syndrome

What is it?

Brachycephalic Obstructive Airway Syndrome, or BOAS, is a term used to describe the changes to the airways in dogs and cats with flat faces. Common breeds affected include the Shih Tzu, Pug, Pekingese, Boxer, all Bulldog breeds, and the Boston Terrier. Some cat breeds are also affected, such as the Persian and Himalayan. All predisposed breeds will have some, or all, components of BOAS.

There are several components to BOAS. All of these make it harder for the animal to breath, because the airway is either too small or being partially blocked. Most brachycephalic animals have stenotic nares and an elongated soft palate to begin with. As the patient ages and continued negative pressure is applied to the breathing structures, further changes may occur. These components are as follows:  

1. Open nares (top) vs stenotic nares (bottom)

  1. Stenotic nares – this means the nostrils are smaller and narrower than they should be, which makes breathing through the nose more difficult
  2. Elongated soft palate – the soft palate is an area of tissue at the back of the mouth, separating the mouth from the nose, just before the opening to the windpipe. If this tissue is too long, it can be sucked into the windpipe as your pet breathes. This results in the characteristic ‘snorting’ noise they may make while breathing, as well as  
  3. Laryngeal saccule eversion – a secondary change due to increased breathing effort. This is the first stage of laryngeal collapse.
  4. Laryngeal collapse – this is a further secondary change, where the cartilage of the larynx loses strength, resulting in collapsing of the entry to the windpipe.  
  5. Tracheal hypoplasia – the trachea, or the windpipe, carries air to the lungs.

Some brachycephalic dogs will have a trachea that is too narrow, which will make breathing more difficult for them.

2. Elongated soft palate in airway (left) and after surgery (right)

3. Normal canine larynx (left), everted laryngeal saccules (blue outline, right)

5. Normal trachea (left) vs hypoplastic trachea (right)

What can be done?

Fortunately, there are procedures available that will make it easier for your pet to breathe, and prevent the development of the secondary changes mentioned above. Diagnosis is based on a clinical exam for stenotic nares, while other changes require examination under general anaesthesia or radiographs. At the time of de-sexing, we recommend a procedure that will widen the nostrils and trim the soft palate back to make breathing easier. This is called a rhinoplasty and soft palate resection.

If your pet is older and secondary changes have occurred, other procedures may be required such as removal of the laryngeal saccules. Laryngeal collapse can be very severe and difficult to treat, so it is highly recommended to perform the rhinoplasty and soft palate resection at the time of de-sexing to avoid this life-threatening secondary change. If this occurs, the patient may require a permanent tracheostomy (a hole into the windpipe on the neck) to allow breathing.

What Can I do to Improve Their Quality of Life?

There are other things that you can do as an owner to make brachycephalic life easier for your pet. As their primary method of cooling is through breathing/panting, these patients are at a much higher risk of suffering from heat stroke. They are also at risk of collapsing due to lack of oxygen, especially as they age and the condition worsens. Brachycephalic dogs should never be exercised when it is hot, so stick to morning and evening walks especially in summer. Heatstroke occurs when an animal overheats and can be fatal. Signs include panting heavily, increased breathing effort, drooling, bright red tongue and gums, and restlessness. Your pet should be kept cool with cool wet towels (never cold or icy), and brought to the veterinarian immediately if you notice these signs.

We highly recommend getting insurance for your brachycephalic pet. BOAS is very common in these dogs, and they are predisposed to several other conditions as well. Their vet bills can get quite expensive, and unfortunately you cannot get insurance coverage once a condition has already been diagnosed (pre-existing). Therefore, we recommend starting insurance as soon as you acquire your new pet. Pet insurance helps ensure that we can all provide the care they require when they need it.

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