Pancreatic necrosis and ventricular erosion in adenovirus-associated hydropericardium syndrome of broilers

Seven 19-day-old broiler chickens affected with hydropericardium syndrome (HPS) with pancreatic necrosis and gizzard erosions were investigated pathologically and virologically. Mortality increased after 13 days of age in a flock on a broiler farm. The mortality rate of the flock reached 10% by 19 days of age. Macroscopically, the chickens had hydropericardium (the characteristic gross change of HPS), pinpoint white foci in the pancreas, and ventricular erosions. Histologically, the chickens had multifocal hepatic necrosis with intranuclear inclusions in hepatocytes, a marked increase of macrophages in the spleen and lung, mild epicardial edema, multifocal necrosis of pancreatic acinar cells with intranuclear inclusions, focal necrosis of the ventricular koilin layer, and degeneration of the ventricular glandular epithelium with intranuclear inclusions. Immunohistochemically, intranuclear inclusions in the liver, pancreas, and ventriculi were stained positively against group I avian adenovirus (GIAAV) antigens. Ultrastructurally, 67-nm diameter viral particles were present in intranuclear inclusions. Virologically, serotype 4 of GIAAV was isolated from the liver, heart, and kidney of affected chickens. The pathologic changes of the present cases differ from previous cases of HPS; therefore, the present strain of GIAAV may have different pathogenicity for chickens than the previous virus strain of HPS.