Peritoneopericardial diaphragmatic hernia(PPDH) is uncommon and congenital disease in dogs and cats. In PPDH, the peritoneal organs such as liver, small intestine, stomach and omentum are displaced into the congenital defect between pericardial sac and diaphragm and cause the abnormal round and enlarged cardiac silhouette. Abnormal cardiac silhouette contacts with the cranial diaphragmatic border consistently and soft tissue- and/or gas- density structures are summated over the cardiac density in radiography. The contrast medium flows from peritoneal cavity into the pericardial sac and demonstrates the herniated abdominal organs and the abnormal defect in positive peritoneography. In this study, 4 dogs was diagnosed as PPDH using radiography, peritoneography and thoracic ultrasonography and showed various clinical signs according to the kind, amount and clinical state of herniated abdominal organs.