Brachycephalic obstructive airway syndrome (BOAS) causes several symptoms. These include noisy breathing, heat intolerance, exercise intolerance, sleep apnea, vomiting, and regurgitation. In severe cases of BOAS, the affected dog may develop cyanosis, collapse, and ultimately die. The symptoms of BOAS progress with age and surgery may be needed to relieve respiratory distress. Symptoms are often aggravated by eating, drinking, exercising, and stress.