Idiopathic pulmonary arterial hypertension in a pot-bellied pig (Sus scrofa domesticus) with right-sided congestive heart failure.

Idiopathic pulmonary arterial hypertension is a rare disease reported in humans and dogs diagnosed as persistent elevation of pulmonary arterial blood pressure without predisposing or associated diseases. A four-month-old pot-bellied pig (Sus scrofa domesticus) was presented for decreased appetite, lethargy, respiratory distress, and occasional syncope. On physical examination, the pig was tachypneic with labored breathing, with a distended abdomen and a bilateral grade 4-5/6 parasternal systolic heart murmur. Systolic pulmonary arterial pressure was estimated at 95 mmHg by Doppler echocardiography, consistent with severe pulmonary hypertension. At autopsy, there was dilation of the main pulmonary artery and right ventricle. The lungs were diffusely rubbery, and there was tricavitary effusion. Microscopically, there was severe widespread pulmonary arterial concentric medial hypertrophy with rare plexiform lesions. The clinical history and gross and microscopic findings supported a diagnosis of idiopathic pulmonary arterial hypertension with subsequent right-sided congestive heart failure. Primary (idiopathic) pulmonary arterial hypertension should be considered as a differential diagnosis in young pigs with right-sided congestive heart failure.