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Breeds at Risk for BOAS and Early Warning Signs

Breeds at Risk for BOAS and Early Warning Signs

BOAS

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Owners

Discover which dog breeds are at risk for BOAS and the early warning signs to watch for, from noisy breathing to subtle changes in sleep and activity

By 

Sustainable Vet Group

Updated on

July 17, 2026

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This article is for informational purposes only and is not a substitute for professional veterinary advice. Every case is unique, so always consult your veterinarian for guidance specific to your pet.

This content is intended for veterinary professionals for educational purposes. It does not replace clinical judgment or tailored advice. Always rely on your training, expertise, and the specific context of your patients.

Breeds at Risk for BOAS and Early Warning Signs

Flat-faced dogs are among the most popular breeds in the US. They are also among the most medically vulnerable.

Not every brachycephalic dog develops clinically significant BOAS. But some breeds are at dramatically higher risk than others, and within those breeds, individual variation means some dogs are much more severely affected than others.

Knowing where your dog sits in this picture is the starting point for responsible care.

 

Quick answer: The highest-risk breeds for BOAS are English Bulldogs, French Bulldogs, Pugs, Boston Terriers, and Pekingese. Research suggests up to 50% of dogs in the three most severely affected breeds have clinically significant breathing obstruction. Early warning signs include noisy breathing at rest, exercise intolerance, overheating, and disrupted sleep. These signs are often normalized but should be evaluated by a veterinarian.

 

Key takeaways

  • Some breeds have BOAS prevalence rates of 50% or higher: This is not a rare condition in the most severely affected breeds.
  • 60% of owners do not recognize BOAS signs as medical symptoms: Normalization delays diagnosis and worsens outcomes.
  • Early signs can be subtle: Reluctance to exercise, restless sleep, and occasional gagging are often the first indicators.
  • Not all brachycephalic breeds carry the same risk: Risk varies significantly by skull shape and muzzle length.
  • BOAS is progressive: Signs that seem manageable at age one may become serious by age three or four without intervention.
  • Puppies should be evaluated early: Veterinary assessment between 6 and 12 months allows intervention before secondary damage develops.

Why breed matters in BOAS

BOAS results from the shortened skull structure of brachycephalic breeds. The degree of risk is closely tied to how extreme the brachycephaly is.

Dogs with very flat faces, extremely short muzzles, and wide skulls have the most compressed nasal passages, the least room for the soft palate, and the highest risk of significant airway obstruction. Dogs with a slightly longer muzzle, even within a traditionally flat-faced breed, tend to have less severe BOAS.

This is why individual dogs within the same breed vary. Two French Bulldogs from different breeding lines can have very different airway anatomy.

Highest-risk breeds

These breeds consistently show the highest rates of clinically significant BOAS in research studies.

English Bulldog

The English Bulldog is widely considered one of the most severely affected breeds.

Bulldogs frequently have stenotic nares, elongated soft palates, and a hypoplastic (narrowed) trachea, which cannot be surgically corrected. The combination of multiple defects makes BOAS management in Bulldogs particularly complex.

Research published in the journal PLOS ONE found that approximately 50% of English Bulldogs, French Bulldogs, and Pugs assessed in studies showed clinically significant BOAS by objective respiratory function testing.

French Bulldog

The French Bulldog has become the most popular dog breed in the US for multiple consecutive years. That popularity has made BOAS in French Bulldogs an increasingly common presentation in veterinary clinics.

French Bulldogs typically have severely stenotic nares and elongated soft palates. They are also prone to aberrant nasal turbinates that further restrict airflow. Exercise intolerance and sleep disruption are particularly common in this breed.

Pug

Pugs are among the most recognizably flat-faced breeds and among the highest-risk for BOAS.

UK research found that around 20% of pugs see a veterinarian specifically for respiratory disease in any two-year period. When objective testing is used, the true proportion with some degree of airway restriction is considerably higher.

Pugs are also common candidates for stenotic nares correction, and pug-specific airway surgery costs and recovery differ somewhat from larger breeds. For the pug-specific picture, the guide on pug-specific surgery cost and recovery covers the detail relevant to pug owners.

Boston Terrier

Boston Terriers occupy a middle position in BOAS severity. Their muzzle, while short, is typically not as extreme as Bulldogs or Pugs, and some individuals have relatively functional airways.

However, within the breed, more extreme conformation is associated with higher BOAS risk. Boston Terriers with more pronounced facial foreshortening and nostril stenosis are more likely to have significant airway obstruction.

Pekingese

The Pekingese is one of the most severely affected breeds in terms of BOAS prevalence. A cross-breed study found that among 14 brachycephalic breeds assessed in the UK, only 10.9% of Pekingese scored Grade 0 (no significant breathing abnormality). This means nearly 90% showed some degree of respiratory dysfunction.

Other affected breeds

A significant number of other breeds carry elevated BOAS risk:

BreedRisk level
Shih TzuModerate to high
BoxerModerate
Cavalier King Charles SpanielModerate
Dogue de BordeauxModerate
Lhasa ApsoModerate
Chinese Shar-PeiModerate
Japanese ChinHigh
Griffon BruxelloisHigh
Bull MastiffModerate

 

Breeds with longer muzzles, such as the Pomeranian and Maltese, show considerably lower rates of significant BOAS despite being classified as brachycephalic.

Early warning signs of BOAS

The signs of BOAS can be divided into those that are obvious and those that are easy to overlook. Both matter.

Obvious signs

Noisy breathing at rest:

Stertor is a low, snoring sound produced in the throat. Stridor is a higher-pitched wheeze that originates from the larynx or trachea. Both indicate airway obstruction. A dog breathing normally at rest should breathe quietly.

Exercise intolerance:

A brachycephalic dog that stops, refuses to continue, or collapses after only a short walk is showing a significant sign. This is not laziness. It is the inability to take in enough oxygen to sustain exertion.

Open-mouth breathing at rest:

Dogs breathe through the nose at rest unless they are hot or just exercised. A dog that routinely breathes through the mouth at rest is unable to move adequate air through the nasal passages.

Coughing or gagging:

Particularly after eating or drinking, or after exertion. Often caused by the elongated soft palate interfering with swallowing.

Subtle signs that are often missed

Reluctance to exercise:

A dog that consistently chooses to stop playing, sit down on walks, or avoid stairs may be doing so because exertion becomes quickly uncomfortable.

Restless or disturbed sleep:

Dogs with BOAS often cannot enter deep sleep because their airway partially collapses when they relax. They wake frequently, reposition, or sleep with their head propped against furniture or the wall to keep the airway more open.

Frequent swallowing and lip-licking:

Often associated with regurgitation and esophageal dysfunction that accompanies BOAS.

Sleeping with the head elevated:

A dog that consistently props its head on the edge of the bed, couch, or a pillow may be doing so to keep the airway aligned and reduce obstruction.

Gastrointestinal symptoms:

Vomiting, regurgitation, and reflux occur in a high proportion of BOAS dogs due to the interaction between respiratory effort and gastrointestinal function.

Signs most commonly normalized by owners

Research has consistently found that approximately 60% of owners of brachycephalic dogs do not recognize signs of BOAS as medical problems.

The following are the most frequently normalized signs:

  • Loud snoring: Often described as "cute" or "just how they sleep"
  • Snorting or snuffling when excited: Attributed to personality rather than anatomy
  • Rapid overheating: Seen as a breed trait rather than a ventilation problem
  • Refusal to walk far: Interpreted as laziness rather than oxygen limitation

 

A dog that cannot breathe freely is not a healthy dog. The flat-faced appearance that owners find endearing comes at a real biological cost, and recognizing that cost is an act of responsible ownership.

 

When to see a veterinarian

Any brachycephalic dog should receive a veterinary airway assessment, regardless of how minor the owner thinks the symptoms are.

Schedule a veterinary assessment promptly if your dog shows:

  • Noisy breathing at rest or during sleep
  • Exercise intolerance disproportionate to their fitness level
  • Frequent gagging, regurgitation, or vomiting
  • Episodes of distress, panic, or labored breathing
  • Blue or purple gums at any point (emergency: go immediately)

Routine evaluation is recommended:

  • For all flat-faced breed puppies between 6 and 12 months of age
  • For adult brachycephalic dogs that have not been assessed

For a clear understanding of what BOAS is and how it develops in the airway, that guide provides the anatomical foundation for understanding why these signs occur.

The importance of early diagnosis

BOAS is progressive. Early-stage stenotic nares and a mildly elongated soft palate become moderate obstruction over time. Moderate obstruction leads to everted laryngeal saccules. Everted laryngeal saccules contribute to laryngeal collapse, which is the most severe and least surgically correctable stage of BOAS.

Dogs treated surgically before age two have significantly better outcomes than those treated later.

Understanding when affected breeds need surgery and managing mild BOAS in at-risk breeds are the two most important next steps for owners of high-risk dogs whose signs are currently mild.

Frequently asked questions

My Frenchie snores but seems happy. Does that mean BOAS is not serious?

Happy behavior does not mean comfortable breathing. Dogs adapt to chronic difficulty and do not communicate discomfort the way humans do. A dog that snores at rest has measurable airway obstruction. Whether intervention is warranted depends on the degree of obstruction, which a veterinary assessment can determine.

Are some individual dogs within high-risk breeds unaffected?

Yes. Not every Bulldog or Pug develops clinically significant BOAS. Dogs with slightly less extreme conformation within their breed may have functional airways throughout their lives. Objective respiratory function testing is the most accurate way to assess individual dogs.

Can BOAS develop later in life, or is it present from birth?

The anatomical abnormalities are present from birth, but the clinical signs often become more apparent as the dog ages. Secondary changes, such as everted laryngeal saccules, develop over time as a result of the chronic breathing strain. This is why a dog that seemed manageable at age one may be more significantly affected by age three or four.

Is there a test to find out how severe my dog's BOAS is?

Yes. Veterinarians use a grading system based on clinical examination, sometimes with mild sedation to assess the soft palate and laryngeal saccules. Some specialist centers use objective respiratory function testing. Most general practitioners can provide an initial assessment and refer to a specialist if surgery is being considered.

Should I avoid buying a flat-faced breed because of BOAS?

This is a personal decision, but it deserves serious consideration. The BOAS welfare issue is significant and well-documented. If you do own or plan to own a brachycephalic dog, committing to early veterinary assessment, appropriate lifestyle management, and surgical intervention if needed is the responsible path.

The popularity of flat-faced breeds has grown dramatically over the past decade. The medical burden that comes with that popularity is real, significant, and mostly preventable through early diagnosis and appropriate care. Knowing which breeds are at risk and what the early signs look like is the most important tool an owner has.

Resources

The following sources were used as reference and background for this article:

  • Liu, N.C. et al. (2017). Conformational risk factors of brachycephalic obstructive airway syndrome. PLOS ONE. ncbi.nlm.nih.gov
  • PetMD. Brachycephalic Airway Syndrome in Dogs. petmd.com
  • Cornell University College of Veterinary Medicine. Brachycephalic Obstructive Airway Syndrome (BOAS). vet.cornell.edu
  • Joii Pet Care. Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs. joiipetcare.com
  • Cross-breed BOAS study. A cross-sectional study into the prevalence and conformational risk factors of BOAS across fourteen brachycephalic dog breeds. ncbi.nlm.nih.gov
  • Today's Veterinary Practice. An Overview of Brachycephalic Obstructive Airway Syndrome. todaysveterinarypractice.com

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