Histopathological Changes in Mule Ducks Infected with Pancreatitis-type Duck Hepatitis A Virus Type 1

Ecchymotic haemorrhage in enlarged livers always serve as an important diagnostic marker for duck viral hepatitis.Recently,a novel duck hepatitis,characterized by yellowed or hemorrhagic pancreatitis,has emerged in some duck farms and the causative agent,named as pancreatitis-type DHAV-1has been isolated.To elucidate the pathological characteristics of the novel duck hepatitis in mule ducks,ten-day-old mule ducks were infected with pancreatitis-type DHAV-1and the pathologic characteristics of disease were observed.The results showed that gross lesion of yellowed or hemorrhagic pancreatitis,without overt change in liver,was observed in infected ducks.Microscopy showed large areas of necrosis in the epithelium,granular degeneration and necrosis in pancreatic cells with no vascular structure were found in necrotic pancreatic areas.In liver,a regular glandular structure around the hepatic venules was formed with lymphocytes and hepatocytes along with focal degeneration,with increase of basophils and infiltration of inflammatory cells found in livers.Focal necrosis was presented in spleen where the white pulp lymphocytes number decreased significantly,and the heterophil infiltration contributed the blurred splenic corpuscle. Based on the above,the results suggested that the gross lesions of pancreatic-type DHAV-1infection in ducklings were characterized by yellowed or hemorrhagic pancreatitis, and the histopathological leisons by large areas of necrosis of the pancreatic epithelium along with granular degeneration and necrosis in pancreatic cells.