What is Brachycephalic Obstructive Airway Syndrome in Dogs?
Brachycephalic Obstructive Airway Syndrome (BOAS) is a breathing disorder that affects flat-faced dog breeds such as Pugs, French Bulldogs and English Bulldogs. It is characterised by breathing difficulties caused by the narrowing of the upper airways due to the shortened skull shape and excess soft tissue typical of these breeds.
These structural changes can lead to several airway abnormalities, including:
Narrowed nostrils: the nostrils are often abnormally narrow, restricting airflow into the nasal passages.
Elongated soft palate: the soft palate at the back of the mouth may be too long and can partially block the airway.
Narrowed windpipe: some dogs may have a narrower-than-normal windpipe (hypoplastic trachea), which can further restrict airflow.
Everted laryngeal saccules: small tissues inside the larynx (voice box) can turn outward into the airway due to increased breathing effort, further obstructing airflow.
Laryngeal collapse: in more severe or long-standing cases, the structures of the voice box may weaken and collapse inward, further obstructing airflow.
Written by Gill Burkhill, Veterinary Surgeon, Animal Trust Vets CIC | Published March 2026 | Review date March 2029 | This advice is for UK pets only and is not a replacement for seeing a vet
Symptoms of BOAS
Dogs with BOAS may show a range of symptoms that vary from mild to severe, including:
Noisy breathing, such as snoring, snorting or wheezing (link to symptoms)
Excessive panting or difficulty breathing
Reduced ability to exercise or tiring quickly
Struggling to cope in hot weather
Disrupted sleep due to breathing problems
Vomiting or regurgitation
Blue or pale gums (a sign of low oxygen)
Fainting or collapse in severe cases
When to contact your vet
If you notice any signs of breathing difficulties in your dog, contact your vet for advice.
Seek emergency veterinary care immediately if your dog:
Is struggling to breathe or breathing becomes very laboured
Collapses or faints
Has blue or pale gums
Appears extremely distressed or unable to settle
Shows signs of overheating and cannot cool down
Breathing problems in flat-faced breeds should always be assessed by a vet, even if the signs appear mild at first.
Diagnosis
BOAS is usually diagnosed based on your dog’s medical history and a clinical examination by your vet.
Your vet will assess your dog’s breathing and examine the structure of the nose, mouth and throat to look for signs of airway narrowing.
In some cases, further tests may be recommended to assess the airway in more detail.
Treatment Options for BOAS
Treatment for Brachycephalic Obstructive Airway Syndrome (BOAS) depends on the severity of the condition and the structures involved.
Surgical treatment of BOAS
Surgery is often recommended to improve airflow in dogs with significant airway obstruction. Procedures may include:
Surgery to widen the nostrils to improve airflow into the nasal passages
Shortening of the soft palate to reduce obstruction at the back of the throat
Removal of everted laryngeal saccules from the larynx (voice box)
Removal of enlarged tonsils if they are obstructing the airway
Surgery can significantly improve breathing and quality of life, particularly when performed before the condition progresses.
Lifestyle management
In some dogs, lifestyle and environmental adjustments can help reduce symptoms and improve comfort. These may include:
Maintaining a healthy body weight to reduce strain on breathing
Managing the environment to minimise heat and avoid breathing distress
Limiting strenuous exercise, particularly in warm or humid weather
Avoiding excessive excitement or stress that may worsen breathing difficulties (for example during play or when greeting visitors)
Using a harness instead of a collar to avoid pressure on the neck and airway
Treating acid reflux or digestive problems with medication and dietary adjustments
See our BOAS Treatment page.
Preventing BOAS
BOAS is linked to the shortened skull shape seen in brachycephalic breeds, so responsible breeding is important in reducing the risk of this condition.
Measures that may help reduce the risk include:
Avoiding breeding from dogs with breathing difficulties or those that require airway surgery
Selecting breeding dogs with good breathing ability and healthier airway structure
Anyone considering a brachycephalic breed should research potential health issues and choose responsible breeders who prioritise health and welfare.
Outlook
BOAS can vary in severity between dogs. Some dogs with mild signs may live relatively normal lives, while others may develop more severe breathing difficulties and related health problems. Early diagnosis and treatment, particularly surgical correction when appropriate, can significantly improve breathing and quality of life. Because BOAS can worsen over time, prompt veterinary assessment and management are important.