Brachycephalic obstructive airway syndrome

A condition affecting short-nosed dog breeds

Brachycephalic obstructive airway syndrome (BOAS) is a pathological condition affecting certain breeds of dogs and cats characterized by a set of upper airway abnormalities. These abnormalities are primarily due to the anatomical structure of the skull in brachycephalic breeds, which are known for their short noses and flat faces.

Anatomy and Pathophysiology

Diagram of brachycephalic dog airway

Brachycephalic breeds have a skull shape that is shorter in length compared to its width, leading to a compressed upper airway. This anatomical configuration results in several structural abnormalities, including:

• Stenotic nares: Narrowed nostrils that restrict airflow.
• Elongated soft palate: The soft palate is longer than normal, which can obstruct the airway.
• Everted laryngeal saccules: Tissue within the larynx that can become everted and further block the airway.
• Hypoplastic trachea: A trachea that is smaller in diameter than normal.

These abnormalities lead to increased airway resistance and difficulty breathing, especially during exercise or in hot weather.

Clinical Signs

Bulldog, a breed commonly affected by BOAS

Dogs and cats with BOAS often exhibit a range of clinical signs, including:

• Noisy breathing (stridor or stertor)
• Exercise intolerance
• Cyanosis (bluish discoloration of the skin due to lack of oxygen)
• Collapse episodes
• Difficulty eating or swallowing

These signs are exacerbated by stress, heat, and physical exertion.

Diagnosis

Diagnosis of BOAS is typically based on clinical signs and physical examination. Veterinarians may perform additional diagnostic tests such as:

• Radiography: To assess the structure of the airway.
• Endoscopy: To visualize the airway and identify specific abnormalities.

Treatment

Stenotic nares before surgery

Stenotic nares after surgery

Treatment for BOAS often involves surgical intervention to correct anatomical abnormalities. Common surgical procedures include:

• Nares resection: Widening of the nostrils to improve airflow.
• Soft palate resection: Shortening of the elongated soft palate.
• Laryngeal saccule excision: Removal of everted laryngeal saccules.

In addition to surgery, management of BOAS includes weight control, avoiding heat stress, and minimizing exercise.

Prognosis

The prognosis for animals with BOAS varies depending on the severity of the condition and the success of surgical intervention. Many animals experience significant improvement in quality of life following surgery.

Breeds Commonly Affected

Exotic Shorthair cat, a brachycephalic breed

Breeds commonly affected by BOAS include:

• Bulldogs
• Pugs
• French Bulldogs
• Boxers
• Boston Terriers
• Persian cats
• Exotic Shorthair cats

Prevention

Preventive measures focus on responsible breeding practices to reduce the prevalence of extreme brachycephalic features. Breeders are encouraged to select for animals with less extreme facial conformation.

Related Pages

• Brachycephaly
• Stenotic nares
• Elongated soft palate
• Hypoplastic trachea