05/09/2025
Brachycephalic Obstructive Airway Syndrome (BOAS)
BOAS Brachycephalic obstructive airway syndrome, also known as BOAS, refers to a number of different anatomical and functional problems that cause breathing problems in certain breeds of dog. These problems include narrow nostrils, overcrowded tissue in the nose cavity, an overly long soft palate, collapse of the larynx and narrowed lower airways (trachea and bronchi). Pugs, French bulldogs and English bulldogs are the most commonly affected breeds in the UK.
Clinical signs:
Dogs with BOAS will frequently show increased breathing noise and effort, particularly when they are excited or exercising. Exercise intolerance, heat intolerance and disturbed sleep may also be noticed. Some dogs will also regurgitate frequently. Clinical signs will often progress with time, and can potentially lead to life-threatening breathing difficulties and collapse in the most severely affected dogs.
Diagnostic investigations:
At the Queenâs Veterinary School Hospital (QVSH), brachycephalic dogs referred for investigations of BOAS will initially undergo the following non-invasive tests:
⢠Clinical examination in the consultation room
⢠Functional grading
⢠Whole-body barometric plethysmography
If the above tests are suggestive of clinically significant BOAS, the following are usually recommended:
⢠Airway examination under anaesthesia
⢠CT scan of the head, neck and chest
⢠Rhinoscopy
Many dogs referred to the QVSH for BOAS surgery will be undergoing investigations and surgery for the first time. However, we also accept referrals for dogs who have undergone surgery elsewhere already, but whose clinical signs have persisted. In many cases these dogs will need some further âconventionalâ surgery, with or without laser turbinectomy, and it may be that this is done in one or two procedures depending on the amount of surgery required.
Prognosis:
Most dogs undergoing BOAS surgery will have reduced breathing noise and effort, improved exercise and heat tolerance and better sleep quality after surgery. Regurgitation may also reduce in frequency. However, surgery is not curative for BOAS, and in some patients clinically significant airway obstruction may remain.
The images attached are of Yoda, a French bulldog who had BOAS surgery at the Queenâs Veterinary school hospital. The first image is before surgery and the second is 8-12 weeks later at his BOAS recheck. Yoda was graded as a grade 2 (moderate) pre surgery and has now come down to a grade 1 (mild) post surgery. His clinical symptoms have improved a great amount and his owner is very happy with the progress made.
