Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs

Does your dog have a short, flat muzzle and does he snore, pant, or wheeze more than you'd expect? Then you may have come across the term Brachycephalic Obstructive Airway Syndrome, often shortened to BOAS. This page explains what is anatomically going on, which dogs are at risk, which signs point to a problem, and when a veterinarian is needed.

Important note beforehand

Important note beforehand: Fidello is not a veterinarian. This page is intended to inform you and does not provide a diagnosis. If you are unsure about your dog's health, or if you recognise the signs described below, always contact a veterinarian. Does your dog show acute breathing distress, severe difficulty breathing, blue or purple gums or tongue, overheating, or a sudden collapse? Then go straight to a veterinarian or veterinary clinic: this can be a life-threatening emergency.

What is Brachycephalic Obstructive Airway Syndrome (BOAS)

BOAS is not a single disease, but a collective term for a combination of anatomical narrowings in the upper airways that occurs more often in dog breeds with a short, flat skull shape (brachycephaly). In these breeds the skull has been bred for a shorter nose-to-mouth length, while the soft tissues in the nose and throat have remained relatively unchanged. This can lead to a combination of overly narrow nostrils, an overly long soft palate, a relatively large tongue, a narrowed windpipe, and swollen mucosal folds in the throat. Together, these features make breathing more effortful than for a dog with a longer muzzle.

Which dogs are at risk

BOAS is most often reported in breeds with a pronouncedly short muzzle, such as the French Bulldog, English Bulldog, Pug, Boston Terrier, Pekingese, Shih Tzu, Cavalier King Charles Spaniel, and Boxer. This link between skull shape and breathing problems has been widely and repeatedly studied and is considered confirmed. The severity varies greatly between individual dogs: not every dog of a sensitive breed is affected to the same degree, and being overweight, high temperatures, and humidity are more often mentioned as factors that make symptoms worse.

Symptoms

Early signs that are more commonly reported:

• Snoring, including during the day while awake
• Loud, snoring, or rattling breathing during exercise or excitement
• Getting out of breath faster than dogs of a similar age from another breed
• Handling heat less well, with faster and heavier panting
• Restless or interrupted sleep

Signs that require urgent care, where a veterinarian or veterinary clinic is needed straight away:

• Clear breathing distress or panic while breathing
• Blue or purple discolouration of the gums or tongue
• Fainting or sudden collapse
• Signs consistent with overheating, such as extreme panting combined with weakness

When to go to the veterinarian

If in doubt, always contact a veterinarian, even if the signs seem mild: persistent snoring or getting out of breath quickly is often seen as normal within many brachycephalic breeds, while it can indeed point to BOAS. A periodic check-up is especially useful before summer, before anaesthesia or a procedure, and when breathing noise gradually increases. With the emergency signs mentioned above, waiting is not responsible: go straight to a veterinarian or veterinary clinic.

How it is diagnosed

A veterinarian bases the initial assessment on breed, symptoms, and physical examination, including the shape of the nostrils. For a fuller picture, further investigation may be needed, such as assessing the soft palate and throat under light sedation, X-rays to assess the windpipe, and in some clinics an endoscopy or CT scan. This assessment is carried out and interpreted entirely by the veterinarian; it is not something an owner can determine at home.

Treatment in broad terms

For milder symptoms, a veterinarian may choose a non-surgical approach, focused on weight, heat, and exercise. For more pronounced symptoms, surgical correction is more often considered, for example widening overly narrow nostrils or shortening an overly long soft palate. Which approach is appropriate depends on the severity and is determined entirely by the treating veterinarian; surgery is no guarantee that all symptoms will disappear.

What you can do yourself

Alongside the treatment a veterinarian determines, there are a few practical things you can pay attention to as an owner:

• Keep your dog at a healthy weight, since being overweight increases the strain on breathing
• Avoid exercise and long outings during hot or humid weather
• Use a harness instead of a collar, so there is no extra pressure on the windpipe
• Provide shade and fresh water, even during short outings
• Let excitement and activity wind down gradually rather than letting your dog work itself up fully

These are supportive measures and not a replacement for veterinary treatment.

Prevention and responsible breeding

At the breeding level, the severity of BOAS in certain breeds is being reduced through objective breathing tests, such as the respiratory function grading scheme developed in the United Kingdom by the Kennel Club and the University of Cambridge. Breeding dogs with a better breathing score are recommended for breeding, with the aim of producing offspring with less pronounced symptoms. Prospective owners can ask a breeder whether the parent dogs have been assessed for respiratory function.

Living with Brachycephalic Obstructive Airway Syndrome (BOAS)

For dogs with ongoing symptoms, it is mainly about adjustments in daily life: a cool environment in summer, gradually built-up walks, a healthy weight, and avoiding situations with a lot of excitement or heat. Regular contact with the veterinarian helps to keep monitoring quality of life over the years and to adjust in time when symptoms increase.

Frequently asked questions

Is snoring in a dog with a flat muzzle always a sign of BOAS?
Not necessarily, but snoring and getting out of breath quickly are sometimes too readily seen as normal within these breeds. If in doubt, have it assessed by a veterinarian.

Does BOAS ever go away completely?
This differs per dog and per severity of symptoms. A veterinarian can assess what is achievable in a specific situation; Fidello cannot make a statement about this.

Can I prevent this if I still have to choose a puppy?
Full prevention is not always possible, but asking whether the parent dogs have been assessed for respiratory function can reduce the risk of severe symptoms in the puppy.

Is BOAS more dangerous during hot weather?
Yes, heat and humidity are more often mentioned as factors that make symptoms worse. Plan exercise for the cooler hours and keep a close eye on your dog during hot weather.

Conclusion

Brachycephalic Obstructive Airway Syndrome occurs in dog breeds with a short, flat muzzle and can range from mild snoring to severe breathing problems. If you recognise early signs in your dog, discuss this with a veterinarian; if you recognise one of the emergency signs, a veterinarian or veterinary clinic is needed straight away.

In closing

In closing: this article does not replace a visit to the veterinarian. Fidello does not provide diagnoses and does not prescribe treatments. If in doubt, with persistent symptoms, or with acute signs, a veterinarian is always the right next step.