Cardiac tamponade secondary to liver lobe torsion and haemopericardium in a Cocker Spaniel with congenital peritoneopericardial diaphragmatic hernia

A 7‐month‐old male Cockapoo presented with tachycardia, muffled heart sounds and bicavitary effusion. Point‐of‐care ultrasound revealed a large pericardial effusion with suspected hepatic tissue within the pericardial sac. Pericardiocentesis drained 200 mL of haemorrhagic fluid, leading to clinical improvement. Abdominocentesis yielded a modified transudate. Computed tomography confirmed a peritoneopericardial diaphragmatic hernia (PPDH) with herniation and torsion of the quadrate liver lobe, resulting in haemopericardium, cardiac tamponade and suspected right‐sided congestive heart failure. Surgical treatment included resection of the torsed lobe and hernia repair. The patient made a full recovery. This case highlights a rare, acute complication of PPDH—liver lobe torsion with secondary cardiac tamponade—not previously reported in dogs. Although PPDH is often an incidental finding, this case underscores the importance of early recognition and advanced imaging in young patients with pericardial effusion and suspected congenital anomalies. Timely intervention was life‐saving.