by Dr. Laurie Zacher, DVM, MS, DACVS-SA
BOAS is a progressive disease that usually presents in dogs between 1-4 years of age but severe cases may be noted at only a few months of age. This syndrome refers to the combination of stenotic nares, elongated soft palate and often secondary everted laryngeal saccules. We are now learning that an additional component contributing to this disease includes the anatomy of the nasal turbinates that can contribute significantly to the airway obstruction. This can be diagnosed by both CT scan and rhinoscopy.
If diagnosed and treated early in life, the goal is to prevent worsening of clinical signs including respiratory distress which if often secondary to laryngeal collapse. BOAS should be suspected when young dogs, particularly pugs, Boston terriers, and French bulldogs, that sound like they are snoring when they breathe. This often is exacerbated by heat and exercise. Owners may also report the dogs frequently retch or gag. Many dogs have concurrent gastritis/esophagitis that should be treated with omeprazole and/or sucralfate. Many dogs’ clinical signs of BOAS will improve dramatically with weight loss and treatment of the gastritis/esophagitis.
The surgical treatment for brachycephalic syndrome has historically included opening the stenotic nares, shortening the elongated soft palate, and trimming the everted laryngeal saccules. Surgery can be performed as young as 3-4 months of age. The outcome is dependent on the age of the dog when surgery is performed and also the severity of the clinical signs. Ideally we like to wait until 9 months to a year of age to perform surgery. If performed when the dog is too young and still has significant growth potential, the surgery may need to be repeated.
Many dogs have good long-term outcomes with mortality rates of <5%. Immediate post-operative complications include respiratory distress and death from post-operative edema. Weight management and exercise restriction during hot days is an important component to lessening the clinical signs associated with brachycephalic syndrome.
A subset of dogs have persistent signs despite the traditional surgery. Recent literature has shown the anatomy of the nasal turbinates can play a significant role in persitance of clinical signs and laser assisted turbinectomy (LATE) can be used to help open the airway in dogs that still have clinical signs with little or no response to the first traditional surgery. It is thought that dogs that mouth breathe at rest are most likely to benefit from this procedure. This is currently being performed in Europe and Illinois.
If brachycephalic syndrome goes untreated, the chronic increase in negative pressure in the pharynx will result in laryngeal collapse as the dog ages. Laryngeal collapse is a form of upper airway obstruction that occurs as the laryngeal cartilage loses its rigidity and allows for deviation of the cartilages into the glottis. There is no good surgical treatment for laryngeal collapse and addressing the palate and nares with an advanced stage of collapse is unlikely to resolve the respiratory problems. Permanent tracheostomy is recommended for patients with advanced laryngeal collapse.