Pulmonary artery thrombosis in three dogs with hyperadrenocorticism.

Varying degrees of respiratory distress developed in 3 dogs in which hyperadrenocorticism was diagnosed. The respiratory distress was attributed to pulmonary artery thrombosis. Radiography revealed pleural effusion, increased diameter and blunting of the pulmonary arteries, lack of perfusion of the obstructed pulmonary vasculature, and overperfusion of the unobstructed pulmonary vasculature. Thrombosis was confirmed by nonselective angiocardiography in each case. In 1 case, selective angiocardiography showed marked reduction of the transit time of contrast medium from the right atrium to the aorta. Hypertension proximal to the site of thrombosis was confirmed in 2 cases by showing increases in the right ventricular systolic pressures (80 mm of Hg in one case and 54 mm of Hg in the other case). In 3 cases, there was moderate hypoxemia with hypocapnia, suggesting a ventilation-perfusion mismatch. Clinical findings other than respiratory distress included hepatomegaly, ventral edema, orthopnea, and a jugular pulse. Pulmonary artery thrombosis, as it occurred in these 3 cases, was compared with the disease in man. It was concluded that pulmonary artery thrombosis should be suspected in cases of intractable dyspnea, right-sided heart failure of unexplained origin, and acute unexplainable death.