− | Animals may remain asymptomatic for years. Typical reported signs include exercise intolerance and dyspnoea as a result of reduced cardiac output and a ventilation perfusion mismatch due to pulmonary oedema. A progressive cough often during rest or recumbency is frequently seen and needs to be distinguished from primary respiratory disease. Sudden death is possible due to a left atrial tear or advanced pulmonary oedema. | + | Animals may remain asymptomatic for years, the disease is usually clinically silent until it is advanced. |