Brachycephalic Airway Syndrome
Brachycephalic airway syndrome (BAS) is a combination of one or more anatomical and functional abnormalities of the upper airway of brachycephalic breeds. Brachycephalic breeds are those dogs with very short muzzles and flat faces, including the Boxer, Bulldog, Pug, Boston Terrier, Pekingese and King Charles Spaniel. Dogs with BAS develop elongation and thickening of their soft palate, chronic pharyngitis, tonsillitis and inflammation and diminished diameter of the larynx and trachea, all of which contribute to variable degrees of respiratory distress. The larynx is the structure situated at the top end of the trachea, behind the root of the tongue. It is lined with mucous membrane tissue and contains the dog’s vocal cords. Another name for the larynx is the “voice box.” The trachea is the tubular passageway between the mouth and the lungs. Brachycephalic airway syndrome is sometimes referred to as brachycephalic upper airway syndrome, brachycephalic obstructive syndrome, upper airway syndrome or brachycephalic syndrome.
BAS is comprised of three main anatomical abnormalities: elongated soft palate, hypoplastic trachea and stenotic nares. The soft palate is the fleshy portion at the back of the mouth (oral cavity) which separates the end of the nasal passages (the nasopharynx) from the back of the mouth (the oropharynx). The soft palate and the hard palate together comprise the “roof of the mouth.” The trachea is the air passageway connecting the mouth to the lungs; hypoplasia is the incomplete development or underdevelopment of an organ or tissue. Nares are the openings of the nasal cavity, commonly referred to as nostrils. Stenosis is the narrowing or contraction of a body opening or passageway. Any or all of these physical abnormalities may be present in a dog affected with SAS.
Brachcephalic airway syndrome (BAS) is caused by several abnormal physical attributes of affected dogs. First, brachycephalic breeds have structural deformities in their skulls and nasal passageways, caused by generations of selective breeding (by people) to create the exaggerated domed heads, broad foreheads, flat faces and almost nonexistent muzzles characteristic of these breeds. The narrowed nostril openings (stenotic nares) that are so typical of dogs with BAS prevent the normal flow of air into the upper
Brachycephalic airway syndrome (BAS) causes obvious respiratory distress in most affected animals. The narrowed nostrils and trachea, together with the overly long soft palate, make it difficult for a dog to breathe in enough air to provide its tissues and cells with a sufficient supply of oxygen.The symptoms of BAS are directly related to the increased airway resistance that is caused by the anatomical abnormalities of an elongated soft palate, stenotic nares and/or a constricted
Brachycephalic airway syndrome (BAS) is not difficult to diagnose. In most cases, a veterinarian can diagnose the condition based on observation of the dog’s breathing and a physical examination. Stenotic nares (narrowed nostril openings) are visibly obvious. Those, together with the characteristic inspiratory snorting sounds of predisposed breeds, are highly suggestive of BAS. A urinalysis and routine blood work (a complete blood count and serum biochemistry profile) frequently are also part of the initial data
The immediate goals of treating a dog with severe breathing difficulty as a result of brachycephalic airway syndrome (BAS) are to remove the upper airway obstruction and restore a patent airway. This can be done by intubating the dog and placing it under general anesthesia, with oxygen and anesthetic gas being provided mechanically to the animal through the endotracheal tube. An open airway can also be established through a surgical procedure called a tracheostomy. This