The term “Brachycephalic Obstructive Airway Syndrome” (BOAS) refers to a group of conditions resulting from the body conformation of dogs with short noses (brachycephalic dogs). Common breeds of brachycephalic dogs include English and French bulldogs, Pugs, Shih-Tzus and Pekingese. Other breeds with longer noses, such as Cavalier King Charles Spaniels and Staffordshire Bull Terriers, can also be affected, although less commonly.
Brachycephalic dogs have narrow/closed nostrils (“stenotic” nares). Also, their nasal cavities are compacted in a small and short nose, making them very tortuous, which increases the resistance to airflow through them. The end of their palate, (called “soft palate”) is too long and thick for their flat face, which makes it obstruct the back of their throat, leading at best to loud “snoring” noises when they breathe, and at worse to complete respiratory obstruction.
Brachycephalic dogs compensate for this anatomy by “pulling” harder when they breathe in (imagine a peg on your nose), which creates strong negative pressures in their throat, neck and chest, which in turn eventually cause secondary respiratory and digestive diseases. This is one of the reasons why brachycephalic dogs frequently regurgitate or vomit.
All brachycephalic dogs have BOAS to some degree. Some are more affected than others. The minimally affected ones can often live their entire life without showing much distress, at the cost of constant excessive efforts to open their throat and breathe. The more affected ones will show various degrees of respiratory distress or digestive troubles, ranging from being occasionally short of breath to collapsing with moderate exercise or high ambient temperatures.
Typically, a brachycephalic dog with BOAS shows a combination of signs such as loud breathing and snoring, intolerance to exercise or heat, collapse, gagging, regurgitation and vomiting. Importantly, what is frequently perceived as being normal “for the breed” is already physiologically abnormal. Having difficulty and making a very strong noise breathing may be widespread among brachycephalic dogs, it does not make it normal or without negative health consequences for that!
As most of the problems included in BOAS result from upper airway obstruction, the main initial focus is unblocking the airways. This is most commonly achieved by surgically widening the nostrils and reducing the length and thickness of the soft palate. In most instances, dogs having undergone surgery will be sufficiently and durably improved to never require any additional surgical treatments for their airways. The earlier that the abnormalities associated with this syndrome are corrected, the better the outcome. The condition worsens over time and may cause other abnormalities. Early correction of stenotic nares and/or an elongated soft palate will significantly improve airway function and may prevent development of everted laryngeal saccules. (The laryngeal saccules are small sacs or pouches that are located just inside the larynx; these saccules evert (turn outwards) or are sucked into the airway by pressure associated with the increased respiratory effort).
If your dog is brachycephalic, you should seek a professional opinion to determine whether he or she would benefit from being treated for BOAS. This surgery is performed at Townsend Veterinary Clinic by Dr. Adrian Wallace and Dr. Peter Young.
Further information on BOAS can be found here:
Photo for comparison. The nostril on the right of the image has been widened