Pulmonary hypertension means there is high blood pressure in the vessel that takes blood to the lungs to get oxygen. When this occurs, obtaining oxygen is difficult and the heart has to work harder against that elevated pressure. Symptoms common with this disease include: significant exercise intolerance, shortness of breath, fainting, hind end weakness, collapse, coughing, and difficulty breathing. This can also lead to right sided congestive heart failure or a fluid accumulation in the belly (ascites). Pulmonary hypertension can be idiopathic (we don’t know the cause) or can occur secondary to: severe left heart enlargement from heart disease, chronic lung disease such as fibrosis or COPD, pulmonary thromboembolism (a clot to the vessel that takes blood to the lung), or heartworm disease.  Some of you will laugh, but the treatment for this disease is Sildenafil also known as Viagra. Viagra relaxes the pulmonary artery and allows the blood to flow to the lungs better improving the clinical signs and symptoms in 2/3 of cases. The prognosis for this disease is variable (usually better with a good response to treatment). However, there is a risk of passing away suddenly at any time with this disease.