Pulmonary arterial hypertension is a state of high blood pressure within the lung (pulmonary) circulation.  

This condition can be due to heartworm disease and embolic disease (clots into the lungs); however, some cases are considered idiopathic (cause unknown).  

Many cases may also develop pulmonary arterial hypertension due to chronic airway disease (pulmonary fibrosis, cancer, or pneumonia).  

This disease process involves damage to the pulmonary arteries and thickening/constriction of these vessels, increasing resistance to flow.  

Medications are utilized to reduce the pulmonary arterial pressures and improve quality of life.  

No medications can return these pressures to normal; however, many patients display a significant improvement in their quality of life.