Histological and Immunohistochemical Evaluations of Lobular Dissecting Hepatitis in American Cocker Spaniel Dogs

Abstract

ABSTRACT. Histological and immunohistochemical evaluations of lobular dissecting hepatitis (LDH) were performed in nine American cocker spaniel dogs. Histological examination showed diffuse fibrosis with weak inflammatory reaction of extensive neutrophils, macrophages, lymphocytes and plasma cells. Immunohistochemical examination revealed that the myofibroblastic cells positive for anti-α-smooth muscle actin and anti-vimentin antibodies produced reticular and collagen fibers and brought about the dissection of hepatic cords and diffuse disappearance of hepatocytes. Reticular fibers invading between hepatocytes and the surrounding small group of hepatocytes were strongly positive for anti-collagen type III and anti-collagen type IV antibodies. The positivity to anti-fibronectin and anti-laminin antibodies was frequently continuous on the basement membrane of the sinusoids of the remaining hepatic cords and between the hepatocytes. Positive findings for anti-E-cadherin antibody were not observed between the hepatocytes showing positive findings for anti-collagen type III and anti-collagen type IV antibodies. These results may explain the expression of fibronectin and laminin that occurs prior to the invasion of reticular fibers between hepatocytes. The present study further suggests that expression of an extracellular matrix mainly containing fibronectin and laminin between the hepatocytes and proliferation of collagen fibers and reticular fibers have a major role in the rupture of the hepatic cords and disappearance of hepatocytes.

ACVIM consensus statement on the diagnosis and treatment of chronic hepatitis in dogs

“…In addition, in Sweden the Scottish Terrier, and in the United Kingdom the Cairn Terrier, Great Dane, Samoyed, Yorkshire Terrier, and Jack Russell Terrier are predisposed . There is some suspicion for a breed predisposition in Standard Poodles and American Cocker Spaniels, which appear to be overrepresented in reports on LDH …”

“…The age of presentation for CuCH and idiopathic CH do not appear to be different. Dogs with LDH present younger than do dogs with CH, with an average age of 2 years (3 months to 7 years, 4 studies with n = 41 dogs) …”

“…Less common but more specific signs of jaundice and ascites occur in approximately 33% of dogs and hepatic encephalopathy (HE) and bleeding tendencies occur in 6%‐7%. Dogs with late stage CH or cirrhosis are more likely to have ascites and gastrointestinal bleeding …”

“…A high incidence of ascites, icterus, and abdominal pain occurs in English Springer Spaniels . American Cocker Spaniels also have a high incidence of ascites and acquired portosystemic shunts (APSS) in the absence of hyperbilirubinemia at the time of presentation . Over 80% of dogs with LDH present with ascites .…”

Hepatic Fibrosis in Dogs

“…It has been reported in a number of breeds, including the Standard Poodle, Rottweiler, German Shepherd, Golden Retriever, and American Cocker Spaniel. This disease has a rapid clinical course and a poor prognosis with a short survival time . Lobular dissecting hepatitis is histologically characterized by a diffuse infiltrate of inflammatory cells and dissection of the lobular parenchyma with reticulin fibers (type III collagen) surrounding single or small groups of hepatocytes .…”