BOAS - breathing problems in flat-faced dogs


  • Brachycephalic means ‘short head’ (flat-faced).
  • Flat-faced breeds are popular because of their loveable nature, but sadly, they often have trouble breathing because of how they look.
  • Flat-faced breeds have a normal amount of tissue packed into a much shorter nose. This means that they often suffer with narrow nostrils, narrow nasal passages, a narrow windpipe and an overlong soft palate. These issues often result in breathing problems (‘BOAS’).
  • Visit your vet for advice if you think your dog may be suffering from BOAS.
  • If your dog develops sudden breathing problems, contact your vet immediately.

What is BOAS?

BOAS simply means ‘problems breathing due to having a short-head’, and sadly, is a result of selective breeding. BOAS commonly affects flat-faced breeds such as Pugs, Pekingese, French Bulldog, British Bull dog, and Shih Tzu. Flat-faced breeds have become popular pets because of their ‘cute’ appearance and good nature – their snuffly breathing often considered loveable. Sadly, in reality, these ‘loveable snuffles’ are a sign that they are struggling to breathe due to BOAS.

BOAS is a combination of the following problems:

  1. Narrow nostrils
  2. Crowded nose and throat
  3. Overlong soft palate
  4. Narrow windpipe

Narrow nostrils

Having narrow nostrils makes breathing difficult; some severely affected dogs have to pant to get enough air.

Crowded nose and throat

Flat-faced dogs have a lot of nose tissue packed into a small space, which means they have to breathe through very narrow, crowded nasal passages.

Overlong soft palate

Flat-faced dogs often have a large soft palate that sits further back than normal. It often covers the windpipe, which makes breathing difficult.

The soft palate can also cause problems during sleep – if it’s covering the windpipe you may notice your dog snoring or waking up suddenly gasping for breath.

Narrow windpipe

A narrow windpipe makes breathing difficult, especially when exercising. Breathing through a narrow windpipe is a bit like trying to breathe through a drinking straw. There are also two sacs inside the windpipe that often become enlarged and cause further problems.

Illustration showing healthy dog nostrils vs narrow nostrils on BOAS dog

1. Narrow nostrils. Click image to enlarge.

Illustration showing healthy dog vs crowded nose and throat on BOAS dog

2. Crowded nose and throat. Click image to enlarge.

Illustration showing healthy dog vs overlong soft palate on BOAS dog

3. Overlong soft palate. Click to enlarge.

Illustration showing healthy dog vs narrow windpipe on BOAS dog

4. Narrow windpipe. Click image to enlarge.


  • Noisy breathing
  • Snoring
  • Panting (even when resting)
  • Unable to exercise properly
  • Struggling to keep up with other dogs
  • Needing regular breaks from exercise
  • Unable to cope with hot weather
  • Sneezing excessively
  • Blue gums
  • Collapse.


Weight control

It’s important to keep flat-faced dogs slim because carrying extra weight will make their breathing worse.


Your dog may benefit from surgery to widen their nostrils and shorten their soft palate. If your dog is severely affected, they may also need the sacs from their windpipe removed. There are risks associated with surgery and it’s important to discuss these with your vet. Your vet may refer your dog to a specialist for surgery.

Outlook and ongoing care

The outlook for your dog depends how severely their breathing is affected. Here are a few tips to help them at home:

Hot days

It’s difficult for flat-faced breeds to stay cool on hot days, avoid the midday sun and only walk them when it’s cool (morning and evening). Monitor your dog during walks and only take them as far as they are comfortable – remember you have to get back! Always take water on walks and if necessary, walk near water so they can cool down easily.


Keep your dog as fit as possible and build their fitness gradually – don’t be tempted to take them for a long walk if they aren’t used to it. Flat-faced dogs often struggle to keep up with other breeds. Put your dog on a lead if they are struggling to chase another. Attach your dog’s lead to a harness not a collar – pressure on their neck will make breathing more difficult.


Flat-faced breeds are prone to weight gain and sadly, many owners of flat-faced dogs resign themselves to the fact their dog is overweight. Being overweight isn’t normal for flat-faced dogs and carrying extra weight will make any breathing problems worse.

Monitor your dog’s weight carefully - speak to your vet or vet nurse about how much to feed them.

Nose comparison between a non-brachycephalic and a brachycephalic dog

A non-brachycephalic dog nose vs. a brachycephalic dog

When to contact your vet

Contact your vet for if your dog has any symptoms of BOAS. If your dog is struggling to breathe, give them first aid and contact your vet immediately.

Buying/rehoming a flat-faced dog

If you are considering buying or rehoming a flat-faced breed, make sure you are aware of any health problems they have, or may develop. Take time to research the breed you are considering and think about whether it will fit into your lifestyle. Speak to your local veterinary practice about breed related health problems and check out our ‘Get PetWise’ quiz.

Own a flat-faced breed?

We understand that many loving pet owners at the time of purchase were unaware of the health problems their pet might face. If you own a flat-faced breed, speak to your vet for advice - surgery and other management options may be available to make sure your dog’s quality of life is as good as it can be. Help us create a healthier nation of dogs – never breed from a dog that has suffered with BOAS, even if they have had corrective surgery. The most sensible option is to have them neutered.


To prevent BOAS, we should only be breeding from healthy dogs and never from a dog with BOAS – even if surgery has improved their symptoms.

A scheme is available to assess Bulldogs, French Bulldogs and Pugs for breathing problems. A specially trained vet scores their breathing from zero to three (zero being the best score and three the worst). Combined scores from an intended mother and father can give an insight into the health of their potential pups. This scheme is a big step towards creating a healthier nation of dogs.


Treating a dog with BOAS can cost thousands of pounds. Consider insuring your dog as soon as you get them, before any signs of illness start. It’s also very important to speak openly to your vet about your finances, the cost of treatment, as well as what you both think is right for your dog. There are often several treatment options so if one doesn’t work for you and your pet then your vet may be able to offer another.

Published: July 2019

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst