BOAS - breathing problems in flat-faced dogs

Overview

• BOAS stands for Brachycephalic Obstructive Airway Syndrome.
• Brachycephalic means ‘short head’ (or flat-faced). Flat-faced breeds often have trouble breathing because of the shape of their head.
• Flat-faced breeds have a normal amount of tissue packed into a much shorter head.
• This means they often suffer with narrow nostrils, nasal passages and windpipe. They also often have an overlong soft palate. These issues often result in breathing problems, known as BOAS.
• BOAS can severely impact your dog’s quality of life.
• If your dog develops sudden breathing problems, contact your vet immediately.

What is BOAS?

BOAS (Brachycephalic obstructive airway syndrome) is a breathing condition that affects flat-faced dogs. It’s caused by selective breeding and can lead to serious health and welfare issues. BOAS commonly affects flat-faced breeds including:

• Pugs
• Pekingese
• French Bulldogs
• British Bulldogs
• Shih Tzus
• Boston Terriers

Flat-faced dog breeds have become popular pets because of their appearance and good nature. Many owners think the snuffles and snoring noises made by their flat-faced dogs are normal, however, these noises are a sign that their dog is struggling to breathe.

BOAS includes one or more of the following primary issues:

1. Narrowed nostrils — meaning less air can get in through the nose and each breath takes more effort. Some affected dogs may only be able to get enough air by panting and breathing through their mouths.
2. Crowded nose and throat — the same amount of tissue that longer-nosed dogs have is packed into a much smaller space, obstructing the airway and adding to the difficulty of getting enough air.
3. Elongated soft palate — a large soft palate (the soft back part at the top of the mouth) blocks airflow into the windpipe, making breathing difficult and resulting in the snuffling/snoring noises in dogs with BOAS
4. Narrow (windpipe) — breathing through a narrow windpipe is a bit like trying to breathe through a drinking straw, it’s very difficult! There are also two sacs inside the windpipe that can be enlarged and cause further problems.

The extra breathing effort these issues create can then lead to secondary problems, for example, collapse of the airway — including the windpipe (trachea) and the larynx (flaps at the top of the windpipe also known as the voice box). Once secondary changes have developed they can be more difficult to treat.

Symptoms

The symptoms of BOAS can appear in puppies but sometimes don’t start until dogs are two – four years old. Symptoms usually get worse over time without treatment and can include:

• Noisy breathing (including snuffles)
• Snoring
• Difficulty breathing
• Disrupted sleep
• Excessive panting, even when resting
• Unable or unwilling to exercise
• Struggling in hot weather (flat-faced dogs are more prone to heatstroke)
• Difficulty eating
• Regurgitation or vomiting — from the pressure created in the abdomen (tummy) from struggling to breathe
• Cyanosis (blue-coloured skin)
• Collapse

Heatstroke and/or a sudden increase in breathing difficulty can lead to collapse and is an emergency.

Diagnosis

BOAS is usually diagnosed based on your dog’s symptoms and an examination. Your vet may ask you to walk your dog for a few minutes to see if exercise brings on or worsens their symptoms. 

Your vet may suggest examining your dog’s airways under a general anaesthetic using an endoscope (a small camera), usually if surgery to improve their symptoms is planned. 

They may also refer you to a specialist, who might carry out further tests, such as a CT scan or to assess your dog using the Royal Kennel Club and University of Cambridge’s Respiratory Function Grading Scheme for BOAS.

Treatment

Keeping an ideal weight  

Flat-faced dogs can struggle with exercise, which means they are more likely to gain weight. Extra weight can make breathing problems worse by putting more pressure around their neck and airways.  

Speak to your vet or vet nurse if you’re worried about your dog’s weight. They can help you check if your dog needs to lose weight and advise you on how to do this safely. 

Exercise

Keeping your dog fit can help them stay healthy but it’s important to build up their fitness slowly. Avoid long walks to begin with if your dog isn’t used to them. Attach the lead to a well-fitted harness instead of a collar as pressure on their neck can make breathing problems worse. 

If your dog is struggling to breathe, slow down and let them rest. Too much exercise can cause their airways to swell, making it harder for them to breathe and increasing the risk of collapse.  

Diet

Feeding your dog the right amount of food can help them stay at a healthy weight. Follow the feeding guide on your dog’s food packaging but remember this is only a guide. Your dog’s needs will depend on their age, size, activity levels and overall health. 

If your dog is prone to weight gain, your vet or vet nurse can help you choose the right diet, portion size and healthy treats.

Surgery  

BOAS cannot be cured, but surgery can improve your dog’s breathing and quality of life.  

Surgery may include widening the nostrils, shortening the soft palate, and removing laryngeal saccules. 

Flat-faced dogs have a higher risk of anaesthetic complications because of the shape of their head and how it affects their airways. BOAS surgery can have serious risks, including breathing problems during recovery. Your vet will discuss the risks and benefits with you. Your dog may also need to be referred to a specialist vet for diagnosis and surgery. 

How well your dog responds to surgery depends on how severe their BOAS is and whether surgery can correct the problems. Surgery may improve their signs, but it cannot completely remove all the effects of BOAS. 

Surgery may help to:  

• Reduced noisy breathing 
• Improve exercise and heat tolerance 
• Improve sleep quality 
• Reduce or stop regurgitation  

Every dog is an individual, so it’s important to speak openly with your vet about the benefits and risks, and what you think is right for your dog. 

Avoid hot weather  

It’s difficult for flat-faced breeds to stay cool on hot days, as dogs lose a lot of heat by panting, which is less effective in dogs with flat faces. They can therefore be very sensitive to heatstroke, which can be fatal. 

On hot days you should only take your dog for short walks when it’s cool (early morning and late evening). If it's too hot all day, then it’s better to skip your dog’s walk until a day when it is cooler. Monitor your dog during walks and only take them as far as they are comfortable — remember you have to get back! 

Always take plenty of water on walks even if it doesn’t seem that hot for you, as this will help them cool down.

Prevention

BOAS is inherited from the parents, so if your dog is suffering from BOAS or any of the symptoms listed above, it’s important not to breed them, even if surgery has improved their symptoms.  

We always recommend thinking very carefully before getting a brachycephalic dog because of the serious health and welfare concerns, including BOAS. Health and welfare is the most important consideration when thinking about getting a dog.   

If you’re considering buying or rehoming a flat-faced breed of dog, make sure you are aware of any health problems they have or might develop. Take time to research the breed and think about whether they will fit into your lifestyle.  

If you still want to buy a brachycephalic puppy, The Kennel Club and University of Cambridge’s Respiratory Function Grading Scheme is available to assess Bulldogs, French Bulldogs and Pugs for breathing problems and can be performed by a specially trained vet. Combining the grades for a sire and dam (mother and father dog) can help to indicate the potential health of their future puppies. 

If you are looking for a puppy from one of these breeds you should check that their parents have a low BOAS grade from this scheme. However, it’s important to remember that a low score doesn’t guarantee the health of the puppy, as genetics can be very complicated.

Outlook

The outlook for your dog depends on how severely their breathing is affected. Struggling to breathe can really affect your dog’s quality of life, so it’s important to get help for your dog, even if they only have mild signs of BOAS. Earlier treatment for BOAS is also likely to have a better outcome.

When to contact your vet

Contact your vet for an appointment if your dog has any symptoms of BOAS, including noisy breathing. If your dog is struggling to breathe, contact your vet immediately. You know your dog best, always contact your vet if you’re concerned.

Cost

Treatment for a dog with BOAS can become very expensive, especially if they need specialist surgery so it’s important to speak openly with your vet about the cost of treatment, your finances, and what you think is right for your dog.  

Consider taking out dog insurance as soon as you bring your dog home, before any signs of illness start. This will give you peace of mind that you have some financial support if they ever become unwell.

FAQs

Published: September 2026