Abstract
A 5-year-old, intact, male Yorkshire Terrier presented with a 6-day history of lethargy and anorexia. Clinical examination revealed dental plaque accumulation, abdominal effort during respiration and muffled heart sounds. Thoracic radiographs revealed an enlarged globoid cardiac silhouette and mild pneumopericardium, transthoracic ultrasonography revealed a pericardial effusion after which pericardiocentesis, cytology and culture diagnosed septic pericarditis. Three multidrug-resistant bacteria were isolated, two of which have been implicated in gas-producing infections before. Medical management failed to resolve the pericarditis and euthanasia was opted for. A chronic osseocartilaginous oesophageal foreign body cranial to the heart base was found on necropsy. Septic pericarditis and pneumopericardium are rare conditions in dogs. This is the first case to describe a multidrug-resistant polybacterial aetiology causing mild pneumopericardium and only the second case to describe septic pericarditis associated with an oesophageal foreign body.