Peritoneopericardial diaphragmatic hernia is the most common congenital pericardial disease in dogs and cats. It results from abnormal development of the dorsolateral septum transversum or from failure of the lateral pleuroperitoneal folds and the ventromedial pars sternalis to unite. The result is herniation of abdominal viscera into the pericardial sac. Liver is most commonly herniated, followed by small intestine, spleen, and stomach. Clinical signs are highly variable, with many patients remaining asymptomatic and the defect being discovered on a necropsy examination. Thoracic radiographs can demonstrate small intestinal loops or liver crossing the diaphragm into the pericardial sac. A contrast radiographic examination using oral barium may also identify small intestinal loops or stomach in the pericardial sac. The diagnosis can be made by the findings of abdominal viscera in the pericardial sac on echocardiography as well. Patients with vomiting, signs of hepatic encephalopathy, or other adverse conditions resulting from PPDH should have a surgical reduction of the hernia.

Last full review/revision April 2012 by Davin Borde, DVM, DACVIM