Pericardial effusion and cardiac tamponade caused by intrapericardial granulation tissue in a dog

Objective – To describe and report successful surgical management of pericardial effusion and cardiac tamponade in a dog caused by intrapericardial granulation tissue.
Case Summary – An 8-month-old, intact male, Greater Swiss Mountain Dog was referred for cardiac evaluation following 2 weeks of progressive lethargy, abdominal distention, and difficulty breathing. On the day of presentation, the dog had an episode of acute collapse. A 14-cm multilocular pericardial cystic lesion causing collapse of the right atrial free wall and resulting in pericardial tamponade was observed on echocardiogram. After the dog subsequently experienced two acute episodes of pericardial effusion, a subtotal pericardectomy was performed and clinical signs resolved. The histopathologic diagnosis of the mass was inflammation and granulation tissue, likely caused by a resolving hematoma or abscess.
New or Unique Information Provided – This is the first report of intrapericardial granulation tissue as the cause of pericardial effusion and cardiac tamponade.