Brachycephalic airway syndrome, also called brachycephalic upper airway syndrome, brachycephalic obstructive syndrome or BAS, refers to several anatomical abnormalities that cause breathing problems in dogs with short muzzles, wide skulls and flat faces. Brachycephalic breeds include Boston Terriers, Boxers, Bulldogs, English Toy Spaniels, French Bulldogs, King Charles Spaniels, Shi-Tzus, Pekingese and Pugs. They are bred for and born with physical deformities in their skulls and nasal passageways that make them have domed heads, broad foreheads and almost no muzzles. They have soft, narrow nostrils that tend to collapse when the dog inhales, and an overly long soft palate (the fleshy portion at the back of the roof of the mouth), both of which interfere with the intake of air. This causes swelling and inflammation of the lining of the nose, throat, voice box and windpipe, creating even more breathing problems. Dogs with BAS snore, snort, gurgle, gag, breathe through their mouth and generally breathe noisily. Their condition gets worse with hot weather, obesity, exertion or stress.