Brachycephalic obstructive airway syndrome

Brachycephalic obstructive airway syndrome (BOAS), also known as brachycephalic airway obstructive syndrome (BAOS), brachycephalic airway syndrome (BAS), and brachycephalic syndrome (BS), is a pathological condition affecting short nosed dogs and cats which can lead to severe respiratory distress. There are four different anatomical abnormalities that contribute to the disease, all of which occur more commonly in brachycephalic breeds: an elongated soft palate, stenotic nares, a hypoplastic trachea, and everted laryngeal saccules (a condition which occurs secondary to the other abnormalities).

Source: Wikipedia — Brachycephalic obstructive airway syndrome (CC BY-SA 4.0)