Brachycephalic obstructive airway syndrome (BOAS) explained

August 11, 2022 - 4 min read
This article is not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your pet’s care, treatment, or medical conditions.
A Bulldog
A Bulldog

Many of us know and love breeds that look a little different than the rest — the group of dogs known as brachycephalic. More common descriptive terms include flat-faced or smushed faced.

While the word brachycephalic has become more widely recognized, many pet parents don’t realize the full implications for their dog.

Here’s what brachycephalic obstructive airway syndrome (BOAS) actually means for our best friends.

So What Exactly is BOAS?

Brachycephalic obstructive airway syndrome, or BOAS, is used to describe a collection of anatomical changes, including the airways and the back of the throat. These changes have slowly progressed over time and can be severe in some pets.

All brachycephalic dogs are affected by BOAS in some capacity. Some may not experience much of a problem regularly, but there are still limitations owners need to be aware of.

Brachycephalic pets have a more flat-faced appearance because they have a more prominent lower mandible (jaw) and a more compacted upper portion of the head. Many can have a significant underbite and teeth crowding because of this.

Generally speaking, the skeletal system and conformation of these types of dogs are small compared to other dogs of the same size.

Unfortunately, the most recognized feature of the brachycephalic is increased sound when they breathe, which is a result of the deformities of their faces and respiratory systems.

People often think this is "OK" or normal for the breed, but these abnormalities do present these dogs with lifelong challenges.

Pug sleeping

Brachycephalic Features

The collection of anatomical changes that make up BOAS includes:

  1. Stenotic Nares: This term means narrowed or skinny nostrils and is a big part of BOAS. When dogs have smaller openings in the nose, this often means they struggle or pant to get more airflow.

  2. Hypoplastic Trachea: This term refers to the trachea (our main, largest airway) having formed too small or not as wide as it should be. Thus, these pets work harder to move air in and out of the lungs as effectively.

  3. Everted Laryngeal Saccules: This term refers to two small areas of tissue on either side of the back of the throat near the cartilage called the larynx. Normally the tissue is tucked inward nicely, but in dogs with BOAS, it is flipped outward and can obstruct airflow.

  4. Elongated Soft Palate: The soft palate is the tissue on top of or at the back of the throat that helps keep the airways and throat separated from each other. Because of the abnormal shape of the brachycephalic pet's skull, this tissue is usually too long and too big for that area and ends up partially or almost fully blocking airflow. Sometimes the dog’s tongue is also too large for the space available, which contributes to difficulty breathing.

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Which Dog Breeds Get BOAS?

BOAS is most commonly recognized in English and French bulldogs, particularly as irresponsible breeding has led to an increase in severity and frequency of these anatomical changes over time. There are, however, many more breeds that can be affected, including:

  • Pugs

  • Boxers

  • Shih Tzus

  • Pekingese

  • Lhasa Apsos

  • Boston Terriers

  • Affenpinschers

  • Brussels Griffons

Even some Staffordshire Bull Terriers, Mastiffs, Chow Chows, and Cavalier King Charles Spaniels can be affected.

Cats and BOAS

BOAS doesn’t only affect dogs! There are several cat breeds that are brachycephalic and can show signs of BOAS, including:

  • Persians

  • Himalayans

  • Exotic/British/American Shorthairs

  • Burmese

Signs and Symptoms of BOAS

Signs of BOAS will vary in type and severity. Things owners should be watching for include:

  • Excessive snoring (including snoring sounds even when awake)

  • Sleep apnea (breathing stops temporarily while sleeping, then abruptly restarts, often waking the pet)

  • Stertorous breathing (increased airway sounds originating in the nasal passages/upper airway)

  • Exercise intolerance (slower during and after activity)

  • Collapse

  • Trouble recovering from warm temperatures

  • Regurgitating or vomiting

Most cases are diagnosed based on the dog’s history and a clinical examination alone. More advanced diagnostic testing, including an anesthetized examination of the larynx and imaging like a head CT scan, can help assess the severity of the disease.

A Side Note on BOAS and Hot Weather

We know that senior pets, overweight pets, and pets with underlying diseases such as heart conditions can suffer much more than healthy pets in hot weather. But brachycephalic breeds suffer the same intolerance to warmer temperatures.

Most healthy adult dogs remain comfortable in temperatures up to around 68 degrees Fahrenheit before we need to be more conscious about what activities we’re doing outdoors with them.

At-risk dogs, including brachycephalics, have an even lower threshold, likely only up to around 63–66 degrees Fahrenheit. This is primarily because moving air through their airways is more difficult, as is panting, so getting rid of excess heat is a challenge.

Some important tips for brachycephalic pet parents in warm weather include:

  1. Avoid activity during the warmest part of the day (i.e., walk only in the early mornings or late evenings)

  2. Be diligent about keeping an eye on the temperature

  3. It’s completely OK to skip your walk if the weather is really toasty

  4. Ensure your pet always has free access to water at home

  5. Be sure to carry water with you when you’re out with your pet

  6. Consider using fans and cooling pads at home, particularly if you don’t have air conditioning

BOAS Treatment and Surgery

While dogs can’t be cured of BOAS, there are a few surgical procedures to help alleviate the issues associated with it.

The most common is the surgical widening of the nostrils, along with removing a portion of the soft palate to shorten it. Our end goal is to decrease the amount of tissue inhibiting the normal flow of air.

It can make a massive difference in the quality of the animal's life. It is, however, important that owners remember that most cases, particularly severe cases, will continue to need support and management over the long term.

Often, your vet will refer you to a specialist for these procedures.

How Much Does BOAS Surgery Cost—and What Else Can I Do to Help?

BOAS surgery can cost well over $1,000, but sometimes there are no better options.

Owners may not be able to fix the problem, but there are a few key points to remember to help your pet if they’re affected by BOAS.

Picking appropriate and safe ways to exercise, avoiding excessively warm temperatures, and maintaining a healthy body weight are all musts when being thoughtful about your brachycephalic pet’s airways!

Buying a Brachycephalic Breed Puppy

Bringing home a brachycephalic breed is definitely a commitment on the owner's part to be a diligent pet parent.

If you’ve got your heart set on a brachycephalic breed like a Pug or a French Bulldog, it’s very important that you look for a breeder who encourages responsible stewardship. This means they are following recommendations to improve breed standards.

Due to a long history of irresponsible breeding and increasing breed popularity, these pets' anatomical genetic abnormalities have become increasingly severe to the point that they are compromising pet health and welfare.

It’s essential that owners are well educated on the health issues associated with brachycephalic breeds. This doesn’t just include BOAS (though that is a major factor).

Some other issues for brachycephalic breeds include:

  • Dermatological disease or allergic skin disease, particularly in areas of facial skin folds

  • Increased risk of eye issues, as many brachycephalic eyes protrude further from the eye orbit due to flat face shape

  • Increased anesthetic risk secondary to abnormal airway anatomy

  • Increased likelihood of gastrointestinal irritation secondary to breathing difficulties

  • Chronic damage to the larynx due to harsh airflow over long periods of time

Despite the challenges, many brachycephalic breeds have legions of affectionate fans, and not just because of how they look. Breeds like Pugs and French Bulldogs have so many desirable qualities that make them fun family dogs that they’re some of the most popular breeds in the US.

But if you’re considering a brachycephalic pup, just make sure you ask the right questions about the parents’ health, know that you’ll be responsible for your new pet’s health, and consider buying pet insurance as soon as you bring them home so they’re covered for any future conditions they may develop.

Veterinary surgeon Dr. Kirsten Ronngren joined ManyPets in 2022. Alongside her extensive experience as a vet in small animal and feline-only clinics, Kirsten is passionate about online content creation. Kirsten’s a regular on ManyPets’ social media and video content with her no-nonsense attitude to keeping our customers’ pets happy and well.