Gross pathology photograph of a duckling with skin, ribs, and keel bone reflected. Notice marked fibrinous adhesions between the epicardium and pericardial sac. The pericardium is diffusely congested, thickened, and adhered to the keel bone ventrally. This is an acute to subacute lesion commonly found in natural infections with Riemerella anatipestifer. Cranial to right of image and caudal to left of image.