Pulmonary hypertension (PH) is a pathologically complex condition with abnormally increased pressure within pulmonary vasculature. PH is frequently diagnosed in dogs and is often associated with high morbidity and mortality. Advanced knowledge and skills are required to diagnose PH, quantify its degree, and determine its underlying etiologies. In this lecture, we will discuss the pathophysiology and the etiologies of PH. This session will also cover the basic and advanced diagnostic and management strategies.