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What Is BOAS (Brachycephalic Obstructive Airway Syndrome)?

What Is BOAS (Brachycephalic Obstructive Airway Syndrome)?

BOAS

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Owners

Learn what BOAS in dogs is, why flat-faced breeds like pugs and bulldogs struggle with it, symptoms to watch for, and treatment options.

By 

Sustainable Vet Group

Updated on

August 26, 2025

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What Is BOAS (Brachycephalic Obstructive Airway Syndrome)?

What Is BOAS in Dogs?

Brachycephalic Obstructive Airway Syndrome (BOAS) is a condition that affects dogs with short, flat faces. These breeds have been bred for their distinctive head shape, but this change in anatomy narrows their upper airways. The shortened skull, along with excess soft tissue in the nose and throat, makes it difficult for them to breathe normally.

BOAS is very common in brachycephalic breeds because their physical traits, while appealing, come at the cost of efficient airflow. Dogs often show signs like noisy breathing, snoring, or difficulty exercising. In severe cases, they may collapse from lack of oxygen.

Breeds most at risk include:

  • Bulldogs (English and French)
  • Pugs
  • Shih Tzus
  • Boxers
  • Boston Terriers

Recognizing BOAS early is key, as untreated cases can greatly reduce quality of life.

Why Flat-Faced Dogs Develop BOAS

Flat-faced dogs develop BOAS because of the way their skull and airway structures are formed. Selective breeding for shorter muzzles has caused several anatomical changes that restrict airflow. Instead of having open, clear passages, these dogs have crowded and narrowed structures that make normal breathing difficult.

The main reasons include:

  • Narrowed nostrils (stenotic nares): Airflow is limited right at the nose.
  • Elongated soft palate: Extra tissue blocks the airway at the back of the throat.
  • Small windpipe (hypoplastic trachea): Less space for air to move into the lungs.
  • Large tongue: Takes up more space than normal inside the mouth.
  • Everted laryngeal saccules: Small tissue folds pulled into the airway, worsening obstruction.

The shortened skull compresses these tissues into a smaller space, creating constant resistance during breathing. This is why brachycephalic dogs often pant, snore, or struggle to cool themselves after mild activity.

Symptoms of BOAS You Should Watch For

Dogs with BOAS often show clear signs that their airway is struggling. These symptoms may appear early in life but tend to worsen as the dog grows older or gains weight. Owners should be alert, because even mild symptoms can progress into serious health problems if not managed.

The most common signs include:

  • Noisy breathing: Constant snoring, wheezing, or snorting even when resting.
  • Exercise intolerance: Dogs tire quickly, breathe heavily after short walks, and may collapse after exertion.
  • Open-mouth breathing: Seen even at rest, which is abnormal for dogs.
  • Gagging or vomiting: Airway obstruction often makes swallowing food difficult.
  • Restless sleep: Dogs wake up often, unable to sleep deeply because of blocked airways.
  • Overheating: Flat-faced breeds cannot cool themselves efficiently, so they pant excessively and risk heatstroke.

These symptoms happen because the airway is too narrow to move enough oxygen. Dogs may also show stress, reluctance to play, or avoid warm environments. Some collapse during hot weather or excitement, which is a medical emergency.

If you notice these warning signs, it is important to seek veterinary advice quickly. Early diagnosis of BOAS helps in planning treatment, ranging from lifestyle changes to surgery, depending on severity. Watching your dog closely ensures they don’t suffer silently from breathing problems.

Hidden Signs Owners Often Miss

Owners of flat-faced dogs often dismiss symptoms of BOAS as normal for the breed. This makes it easy to miss important early warnings. Here are some subtle signs that should not be ignored:

  • Heat intolerance: Often mistaken for laziness. Dogs avoid activity in warm weather because they cannot cool themselves effectively.
  • Exercise refusal or collapse: A dog that stops suddenly during play, or even collapses, may be struggling to breathe rather than just being tired.
  • Restless sleep: Snoring is common, but frequent waking or shifting during the night signals airway obstruction. Poor sleep affects daily energy and recovery.
  • Gagging or difficulty swallowing: Owners may overlook gagging after meals, but this often links to airway pressure and throat tissue obstruction.
  • Normalization of symptoms: Many assume snorting, open-mouth breathing, or noisy inhalation is “just how the breed is,” when in fact these are medical issues.

When such signs are missed, BOAS continues to progress, reducing comfort and increasing risk of heatstroke or sudden collapse. Recognizing them early ensures timely veterinary care and a better quality of life.

Secondary Complications of BOAS

BOAS does not only affect breathing. The condition also creates strain on other systems in the body, leading to secondary complications that can lower a dog’s overall health. Many of these problems are less obvious but still serious.

  • Gastrointestinal reflux and regurgitation: Struggling to breathe puts pressure on the digestive tract, causing food or stomach acid to move back up. This leads to vomiting, regurgitation, or chronic esophagitis.
  • Dental crowding and malocclusion: Shortened jaws in brachycephalic breeds leave little room for teeth, leading to crowding, abnormal bite, and higher risk of gum disease.
  • Eye problems: Shallow eye sockets mean less protection. Dogs are prone to corneal ulcers, pigmentary keratitis, and chronic irritation due to prominent eyes.
  • Skin fold infections: Deep facial folds trap moisture and bacteria, resulting in dermatitis, itching, and recurrent infections.
  • Anesthetic risks: Narrowed airways and abnormal anatomy make it harder to maintain safe breathing during anesthesia, increasing surgical risks.

These complications highlight how BOAS is not limited to the airway but affects multiple organs. Regular monitoring and early veterinary care can reduce the impact of these problems and improve long-term well-being.

How BOAS Impacts a Dog’s Quality of Life

Living with BOAS places constant strain on a dog’s body. The extra effort required for every breath means that affected dogs often experience fatigue, even during normal daily activities. What seems like laziness is usually a sign of poor oxygen supply.

  • Reduced activity: Dogs cannot play or exercise for long without panting, wheezing, or collapsing.
  • Heat intolerance: Their impaired ability to pant makes them very sensitive to warm environments.
  • Risk of heatstroke: Even mild heat exposure can lead to dangerous overheating, which can be fatal without immediate care.
  • Sleep disturbance: Snoring and frequent waking prevent full rest, leading to irritability and weakness.
  • Shortened lifespan: Studies show that severe BOAS reduces life expectancy compared to non-brachycephalic breeds.

BOAS affects more than physical health. Dogs may develop anxiety, frustration, or behavioral changes due to limited ability to interact and enjoy normal activities. For many, this condition quietly reduces daily comfort and long-term well-being unless recognized and managed early.

Diagnosing BOAS in Dogs

Diagnosis of BOAS requires careful veterinary assessment, as symptoms often overlap with other health conditions. A full examination helps determine severity and guide treatment.

  • Physical examination: Vets assess nostril shape, breathing patterns, and airway sounds.
  • Imaging and endoscopy: X-rays, CT scans, or a camera in the airway reveal structural issues like elongated soft palate or narrowed trachea.
  • Respiratory Function Grading (RFG): This scale ranges from 0 (no clinical signs) to 3 (severe compromise). It helps standardize diagnosis and track progression.
  • Exercise tolerance tests: Some clinics use short exercise challenges to assess breathing function under stress.

Early diagnosis is crucial. Many owners assume noisy breathing is “normal,” but catching BOAS early allows for better lifestyle adjustments, weight control, and planning surgery before life-threatening complications develop. Routine veterinary check-ups are the best way to detect BOAS before it severely impacts quality of life.

Treatment and Management Options

Managing BOAS requires a mix of medical care, surgery, and lifestyle changes tailored to each dog. Treatment depends on severity and overall health.

  • Weight management: Obesity worsens breathing problems. A balanced diet and controlled feeding reduce strain on the airway.
  • Lifestyle adjustments: Owners can help by avoiding heat, limiting intense exercise, and using harnesses instead of collars to prevent throat pressure.
  • Surgical options: Common procedures include widening narrowed nostrils, shortening an elongated soft palate, and removing everted laryngeal saccules. These surgeries can significantly improve airflow and quality of life.
  • Risks and challenges: Anesthesia is higher-risk for brachycephalic breeds due to their narrow airways. Even after surgery, some symptoms may persist or recur.
  • Lifelong care: Most dogs require ongoing monitoring, diet control, and environmental adjustments to stay comfortable.

While treatment cannot fully reverse BOAS, timely surgery and careful management allow many flat-faced dogs to live longer, healthier, and more active lives. Owners play a key role in maintaining their dog’s comfort after intervention.

Preventing BOAS in the Future

Prevention of BOAS begins with responsible breeding. Since the condition is linked to skull shape and airway anatomy, selective breeding plays a major role in reducing its occurrence. Breeders should prioritize health over extreme appearance standards and avoid producing dogs with severe brachycephalic features.

  • Responsible breeding practices: Focus on wider nostrils, shorter soft palates, and less extreme facial shapes.
  • Avoiding breeding affected dogs: Dogs showing clinical signs of BOAS should never be used for breeding, as this passes the problem to future generations.
  • Early puppy screening: Veterinary checks can identify narrowing or obstruction in young puppies, allowing for early management or removal from breeding programs.
  • Owner education: Prospective owners should be informed about the risks of flat-faced breeds and encouraged to support breeders who prioritize health.

Preventing BOAS is not only about reducing suffering but also about ensuring a healthier future for these beloved breeds.

Special Concerns for Owners of Flat-Faced Dogs

Owning a brachycephalic dog requires extra care. Because their anatomy places them at higher risk, owners must be aware of special concerns throughout the dog’s life.

  • Air travel restrictions: Many airlines limit or ban flat-faced breeds, as reduced cabin airflow and stress make them prone to collapse.
  • Exercise in hot or humid weather: These dogs cannot cool themselves efficiently, so activity should be restricted during warm conditions.
  • Ongoing veterinary care: Regular check-ups are essential to monitor breathing, weight, and secondary complications.

With careful management, many dogs can still enjoy a good quality of life, but owners must remain proactive and attentive at all times.

Conclusion

BOAS is a serious health problem that affects many flat-faced dog breeds. It develops because of structural changes in the nose, throat, and windpipe, making every breath more difficult. While some owners may see noisy breathing or snoring as normal, these are warning signs of airway obstruction that can shorten a dog’s life.

Awareness is the first step in protecting affected dogs. With early diagnosis, lifestyle changes, and when needed, surgery, many dogs can live more comfortably and safely. Regular veterinary monitoring is essential, as BOAS often progresses with age or weight gain.

In the long term, prevention lies in responsible breeding. Reducing extreme facial traits and avoiding breeding affected dogs are the only ways to lower BOAS prevalence. By focusing on health over appearance, we can improve the lives of future generations of flat-faced dogs.

FAQs

What breeds are most affected by BOAS?

Breeds most affected by BOAS are those with flat faces and shortened skulls. These include Bulldogs (English and French), Pugs, Boston Terriers, Shih Tzus, and Boxers. Their unique anatomy narrows the airways, making breathing difficult. Selective breeding for extreme facial traits increases the risk of this condition in these dogs.

Can BOAS be cured completely?

BOAS cannot be cured completely, but it can be managed effectively. Surgery can improve airflow by widening nostrils, shortening the soft palate, or removing tissue blocking the airway. Lifestyle changes such as weight control, avoiding heat, and regular monitoring are also important. Even with surgery, lifelong care is usually required to maintain comfort.

How can I tell if my dog’s breathing problem is serious?

If your dog struggles to breathe at rest, collapses after exercise, snores loudly, or cannot tolerate heat, it may be serious. Other warning signs include gagging, vomiting, or restless sleep. Any sudden worsening of breathing, especially in warm weather, is an emergency. Veterinary evaluation is the only way to confirm BOAS severity.

Is surgery safe for flat-faced dogs with BOAS?

Surgery can be life-changing for dogs with BOAS, but it carries increased risk. Flat-faced breeds have narrowed airways that complicate anesthesia. With an experienced surgical team and careful monitoring, surgery is generally safe and successful. However, some dogs may still have residual symptoms, and careful post-operative care is essential for best results.

How long can a dog with BOAS live?

Life expectancy depends on severity and management. Mild cases, with proper weight control and care, may live normal lifespans. Severe untreated BOAS can shorten life due to collapse, heatstroke, or chronic strain. Dogs who undergo corrective surgery and receive lifelong monitoring usually enjoy longer, healthier lives compared to those left untreated.

Can BOAS be prevented in puppies?

BOAS cannot be fully prevented in individual puppies already born, since it is tied to skull anatomy. However, responsible breeding can reduce future cases. Avoiding breeding affected dogs and screening puppies early helps lower risk. Education for new owners and choosing breeders who prioritize health over appearance are vital preventive steps.

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