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Brachycephalic Obstructive Airway Syndrome (BOAS)


Brachycephalic Obstructive Airway Syndrome (BOAS) is a breed related disorder that significantly compromises the way pets breathe. 

Brachy means shortened and cephalic means head, so animals affected are “flat-face” breeds including French Bulldog, Boston Terrier,Pug, Boston Terrier, Boxer, British Bulldog, and Shih-tzu.  


What is it?

  • Combination of upper airway abnormalities that cause partial obstruction to a dogs breathing. 

    • Stenotic nares – small, narrow nostrils that may collapse when breathing in. Makes it difficult for the dog to breathe through its nose

    • Elongated soft palate – soft tissue behind the hard palate (roof) of the mouth. If too long it extends into the airway and interferes with movement of air into the lungs

    • Everted laryngeal saccules – soft tissue structures near the vocal folds and larynx (start of the trachea/windpipe) that can become inflamed and everted (turned out). Everted saccules can get pulled into the trachea, obstructing airflow

  • Many dogs will only have one or two of these conditions, but they can cause enough breathing trouble on their own that they need to be addressed.

  • Some dogs also have a narrow trachea or laryngeal paralysis


Who does it affect?

  • Brachycephalic breeds. Brachycephalic means short-headed. These dogs have been bred to have shorter muzzles, flat faces and squished noses, which has lead to malformations in the upper airways.

  • Bulldogs (including French Bulldogs), Pugs, Boxers, Shih Tzus, Boston Terriers, Pekingese and Chow Chows and their crosses


What to look for

  • Noisy breathing, especially on inhalation (snorting)
  • Snoring while sleeping
  • Increased breathing effort
  • Exercise intolerance (tiring easily)
  • Retching or gagging, especially when swallowing
  • Nasal discharge (stenotic nares)
  • Blue tongue and gums (from lack of oxygen)
  • Fainting or collapse (loss of consciousness) – can be fatal

Generally worse after exercise, excitement, excessive heat/humidity. Signs worsen with obesity. We can diagnose stenotic nares on a routine physical exam, and suspect elongated soft palate and everted saccules based on clinical signs and history, but we can only diagnose and assess severity of the latter conditions on a sedated dog, as dogs rarely allow us to look at the back of their throats for an extended period of time, and often their tongue is in the way. A sedated upper airway examination will allow us to accurately diagnose and come up with an appropriate treatment plan (which will likely include surgery) to allow your dog to breathe easier.


How to help minimise breathing issues at home

  • Limit expose to heat and humidity – inside in air conditioning on hot days
  • Make sure exercise is not too strenuous – indoors or at cooler times of day
  • Use a harness instead of a neck collar
  • Teach your dog to have self control, keep them calm, train them to settle down


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Pets Health is a full service animal hospital with clinics located in Hilton and O’Halloran Hill. We are dedicated to helping you keep your best mate happy and healthy through each stage of their life with compassionate and reassuring veterinary care.

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O’Halloran Hill Vet Centre

123 Main South Road
O’Halloran Hill, SA 5158

Hilton Vet Centre

142 Sir Donald Bradman Drive
Hilton, SA 5033