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Brachycephalic Syndrome & Obstructive Airway Disease (BOAS)

Brachycephalic Syndrome is a common breathing condition that can affect flat-nosed dogs and cats. Veterinarian Joanna Woodnutt provides details about the symptoms, prevention, and possible treatment options. No one likes to see their pet suffer, so knowing you to prevent or ease your dog's symptoms can go a long way towards an improve quality of life.

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Last Updated: January 6, 2022 | 6 min read

Pug with Brachycephalic Syndrom

BOAS stands for Brachycephalic Obstructive Airway Disease and is sometimes referred to as Brachycephalic Syndrome. It refers to a condition affecting short-nosed dog breeds that causes difficulty breathing due to a narrowed airway.

BOAS can affect different dogs to varying degrees. Some brachycephalic dogs may be severely affected while others suffer from milder symptoms.

The good news is that there are many things you can do to help manage your pet’s condition. Learn more about this disease and the important steps you can take to improve your brachycephalic dog’s quality of life.

What Is BOAS?

Pug panting
BOAS is a collection of conditions affecting the upper airway of brachycephalic breeds, resulting in breathing problems.

Dogs (and cats) with short noses and compacted skulls are referred to as ‘Brachycephalic. Popular brachycephalic dog breeds include English Bulldogs, French Bulldogs, Shih-Tzus, and Pugs, although there are several more. The most common brachycephalic cat breed is the Persian. It is these brachycephalic breeds that suffer from BOAS.

The flat faces of these breeds result in a malformed airway, causing difficulty breathing. Their nasal cavities are much shorter than other dog breeds, and they frequently also have narrowed nostrils, both of which restrict the airflow when they breathe. Their compacted skulls mean that brachycephalic breeds’ soft palate is too-long, creating excessive soft tissue at the back of their throats. This further obstructs the airways, making it even more challenging to breathe.

List Of Brachycephalic Dog Breeds

Here is a comprehensive list of brachycephalic dog breeds:

AffenpinscherBoxerBrasileiroBrussels Griffon
BulldogBullmastiffBoston TerrierCane Corso
Cavalier King Charles Spaniel Chow ChowDogue de BordeauxEnglish Toy Spaniel
French BulldogJapanese Chin Lhasa ApsoPekingese
PugShar PeiShih Tzu Staffordshire Bull Terrier

What Are The Symptoms?

BOAS can make dogs irritable, just as breathing difficulties do in humans.

Narrow Nostrils (‘Stenotic Nares’)

A brachycephalic dog’s nostrils are often very narrow and can collapse inward when they breathe in, meaning that it is nearly impossible for them to breathe through their noses. Additionally, dogs with stenotic nares often have a nasal discharge that worsens the airflow through their noses.

Noisy Breathing

Most brachycephalic dogs make abnormally loud sounds when they breathe, such as gagging and snorting. Most BOAS-affected dogs snore while sleeping, and often snore when awake too.

Digestive Issues

Dogs affected by BOAS also frequently gag while eating or drinking and are prone to regurgitation and vomiting. This is because the excess tissue of the soft palate can impede swallowing, sometimes resulting in the accidental inhalation of food or liquid. If this happens, secondary infections of the respiratory tract, such as pneumonia, can develop, further worsening breathing.

Sleep Deprivation

Dogs suffering from BOAS also have difficulty sleeping. This is because as they fall asleep, the soft palate and all the excess tissue relaxes, obstructing the airway even more than it does when they are awake. This causes them to choke, waking them up and leading to an ongoing cycle of chronic sleep deprivation. This lack of sleep can lead to behavioral problems.

Exercise Intolerance

The difficulty in breathing that affects dogs with BOAS means that they struggle to breathe fresh air into their lungs and meet their oxygen requirement. During exercise, oxygen demand increases, and BOAS dogs often struggle to increase their air intake. BOAS dogs that struggle to oxygenate can suffer from cyanosis, signaled when their gums turn blueish-purple. This often results in collapse and can be life-threatening. Dogs severely affected by BOAS can sometimes collapse after minimal exertion or exercise.

Heat Intolerance

A dog’s nasal cavity plays a crucial role in his ability to cool down in the heat. BOAS-affected dogs have much smaller and narrower nasal cavities than other dogs, significantly decreasing their ability to regulate their body temperature and cool themselves down. This makes them prone to overheating or heatstroke, which can be life-threatening.

Reverse Sneezing

Reverse sneezing is common in dogs with BOAS and is thought to be caused by the excessive soft tissues of the soft palate, causing throat irritation. Episodes usually last a few seconds but can sometimes continue for longer. Reverse sneezing doesn’t usually require treatment but talk to your veterinarian if it affects your dog’s day-to-day life.

How Is BOAS Diagnosed?

Bulldog in sun with tongue out
A general anesthetic is required to fully assess the soft palate.

BOAS is often diagnosed based on the clinical signs mentioned above. Veterinarians will perform a complete physical examination and assess the dog’s conformation and breathing. The degree to which a dog suffers from BOAS can also be assessed using a grading system performed by a veterinarian. These are based on clinical assessments pre-and post-exercise and usually include an exercise tolerance test.

X-rays and CT scans can help you understand the severity of BOAS. Chest x-rays are used to determine whether there are any secondary complications of BOAS, such as aspiration pneumonia. CT scans can demonstrate how much excess soft tissue there is and how thick it is, and also assess the skull conformation. Rhinoscopy (passing a tiny camera) can be very useful to evaluate the nasal cavity and identify the degree of nasal obstruction.

Can BOAS Be Treated?

Boxer running with tongue out
If your dog is overweight, weight loss may be recommended before surgery is performed.

BOAS is not curable, but sometimes surgery can be performed to give your dog a significantly improved quality of life. Several different types of surgery are available, depending on the severity of symptoms and the most problematic areas of your dog’s anatomy.

A vet can surgically widen nostrils to increase the ability of your dog to breathe through his nose. It is also possible to surgically shorten and thin the soft palate, which can help to open up your dog’s airway to allow better airflow. Sometimes the tonsils also need to be partially removed which again, helps to improve your dog’s ability to breathe.

Over time, dogs affected by BOAS left untreated can develop secondary problems whereby their larynx (voice box) periodically collapses. This can happen to differing degrees, but further narrows their airway. Surgery referred to as a ‘tie-back aims to widen the airway again.

Risks And Prognosis

Any form of corrective surgery could significantly improves the quality of life for dogs severely affected by BOAS. However, more mildly affected dogs can benefit from surgery too. Most dogs recover very quickly afterward and can usually go home within 24 hours. They should be rested at home for 7-10 days following surgery, but they can return to their normal routine after that.

The greatest risk associated with any airway surgery is post-operative swelling. Your dog may require a temporary tracheostomy tube (tube placed directly into the windpipe) to allow him to breathe while the swelling subsides. Accidental inhalation of food or liquid into the airway leading to aspiration pneumonia can be another risk after airway surgery. Surgeries may have different success rates depending on the severity of BOAS. Dogs with severe BOAS symptoms may require repeat surgeries in the future.

How Do I Manage My Dog’s BOAS?

Close up of a big overweight white bulldog looking in the camera with his tonque sticking out
For an overweight brachycephalic dog, losing weight can significantly improve their ability to breathe.

Maintain A Healthy Weight

The most important factor that can significantly worsen the effects of BOAS is obesity. Excess body fat results in fatty tissue being deposited around the airways, making them even narrower than they already are. This makes it yet even harder for your dog to breathe properly. Speak to your veterinarian about your dog’s ideal weight, and if necessary, start a weight loss program to help him achieve it.

Avoid Overheating

Dogs with BOAS have difficulty regulating their core body temperature, making them more prone to overheating. If you have a dog with BOAS, avoid walking him on hot days and ensure he always has somewhere to cool off if needed. Do not excessively exercise him and avoid high levels of stress or excitement wherever possible. Signs of heatstroke include excessive panting, a raised body temperature, excessive drooling, a rapid heart rate, staggering, and even seizures. Heatstroke can be life-threatening, so contact your veterinarian immediately if you suspect your dog has overheated.

Can BOAS Affect Cats?

BOAS-affected cats often suffer from many of the same problems that dogs do. Noisy breathing, gagging, and snoring are all common symptoms in cats as well as dogs. Some severely affected cats breathe through their mouths or pant – something which is very abnormal for cats and often indicates severe respiratory distress. This is usually seen after exercise or at times of stress, such as a visit to the vets.

Cats can have corrective surgery for BOAS, just in the same way that dogs can. Weight management is also just as important, and one of the best things you can do to help your cat is to ensure that he maintains a healthy weight.

Final Thoughts

All brachycephalic dogs suffer from BOAS to some extent, but some are more severely affected than others. It is important to realize that just because signs like noisy breathing and gagging can be ‘normal’ for these brachycephalic breeds, these are also signs of breathing problems that should be addressed. Getting dogs with longer snouts and putting pressure on breeders to focus on health, not looks, is one of the key ways we can reduce BOAS among the dog population in the future.

Corrective surgery can often significantly improve the quality of life for these breeds, but surgery should never be taken lightly. Talk to your veterinarian for more advice on the management of BOAS and whether or not corrective surgery could benefit your pet.

Health Disclaimer: The information provided through this website should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.

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