Prednisone-induced morphologic and chemical changes in the liver of dogs.

Glucocorticoid treatment in dogs is known to cause hepatocellular swelling due to accumulation of cytoplasmic compounds which variably have been identified histochemically as fat, glycogen, or water. In the present study changes in dog liver, after treatment for 15 days with two different doses of oral or intramuscular prednisone, were examined using histological, histochemical, and ultrastructural techniques as well as quantitative chemical analysis. Thirty mongrel dogs were divided into two control groups and three treatment groups of six dogs each. Dogs which received prednisone orally at 1.2 mg/kg body weight/day, or 4 mg/kg body weight/day, respectively, or received intramuscular prednisone injections of 4 mg/kg body weight/day had hepatomegaly due primarily to hepatocellular accumulation of glycogen. Compared to controls, no changes in the hepatic water concentration were observed, whereas the relative amounts of liver fat were decreased slightly and those of protein were decreased markedly. Hepatocellular glycogen could be demonstrated histochemically in tissues fixed in absolute alcohol, but not in tissues treated with aqueous fixative, such as 10% buffered formalin or Bouin's solution. Glycogen deposition occurred predominantly in the midzone of hepatic acini. Affected hepatocytes varied in size and shape. The most severely affected cells were enlarged five to ten fold with glycogen occupying most of the cytoplasmic space restricting the mitochondria, endoplasmic reticulum, and other organelles to a narrow zone around the cell periphery and the nucleus. It was concluded that treatment with prednisone causes hepatomegaly due to glycogenosis in the dog.