Brachycephalic Obstructive Airway Syndrome

Brachycephalic Obstructive Airway Syndrome (BOAS) is the term given to the effects that the shortened animal head has on the passage of air through the upper airways.

Clinical signs can vary in severity from mild snoring or snorting noises to severe breathing problems.

Animals affected by BOAS can struggle to breathe during exercise but also during warm weather: dogs relying on panting to cool themselves down are very susceptible to overheating and developing potentially very serious breathing difficulties.


Breed susceptible to BOAS:

Brachycephalic breeds include those breeds of dog and cat that have an obvious, characteristic short or squashed nose appearance. Any breed of dog or cat with a brachycephalic head conformation can be affected.


  • English Bulldog
  • French Bulldog
  • Dogue de Bordeaux
  • Boxer
  • Pug
  • Cavalier King Charles Spaniel
  • Lhasa Apso
  • Shih Tsu
  • Pekingese
  • Other brachycephalic breeds


  • Persian
  • Himalayan

Clinical Assessment of BOAS:

Traditionally, veterinary practices use physical examination, behavior tests, anatomy assessments, and exercise tolerance tests (ETT). Other tests may include:

  • Blood tests/cardiac assessment
  • Chest X-Ray
  • Full airways assessment (traditionally performed under general anesthesia)
  • Endoscopy
  • Unrestrained whole body plethysmography (WBP)

The classification and severity of BOAS can vary between the different brachycephalic breeds. Obesity and stenotic nares are often considered risk factors for BOAS. Clinical grading is performed before and after ETT. 

DSI and Whole Body Plethysmography:

The use of whole body plethysmography eliminates the need for clinical assessment under anesthesia or restraint. Using DSI's WBP solution, the animal will remain conscious, freely moving and unrestrained allowing for a stress free measurement of the animal (and the reassurance of its owner). 

Primary endpoints of interest include respiratory rate, peak inspiratory and expiratory flow, tidal volume, and minute volume. 

DSI solutions are helping small animal veterinary hospitals and animal health researchers to objectively gather respiratory endpoints and properly classify the severity of BOAS. Learn more about these solutions below.

BOAS articles citing DSI in Google Scholar

FPWBP – When conscious, unrestrained approaches are desired, FinePointe whole body plethysmography allows for respiratory endpoints to be obtained. This approach is often used as a quick, easy way to obtain baseline values, run longitudinal studies, and assess the success of (or need for) surgical intervention to help treat the patient.  

Learn more about FinePointe whole body plethysmography products.


FinePointe Software – FinePointe software is powerful and easy-to-use for collecting, analyzing, and reporting life science data. Fully network-enabled, the smart design minimizes required user interaction while wizards walk users through necessary procedures.

Learn more about Buxco FinePointe software from DSI.

FinePointe Website_Circle Image


Davis M, Cummings S, Payton M. "Effect of brachycephaly and body condition score on respiratory thermoregulation of healthy dogs." J:  Am Vet Med Assoc 2017;251:1160–1165.

Bernaerts F, Talavera J, Leemans J, Hamaide A, Claeys S, Kirschvink N, Clercx C. “Description of original endoscopic findings and respiratory functional assessment using barometric whole-body plethysmography in dogs suffering from brachycephalic airway obstruction syndrome.” The Veterinary Journal. 2010;183:95-102.