The pathology of halothane hepatotoxicity in a guinea-pig model: a comparison with human halothane hepatitis.

The pathology of halothane hepatotoxicity is described in detail in a guinea-pig model. Twenty-two of 40 guinea-pigs developed liver damage after exposure to 1% halothane in 21% O2 for 4 h. The other 18 animals showed no evidence of hepatic injury. Two distinct patterns of damage were identified: mild damage, in which livers had focal areas of necrosis, and severe damage, where necrosis was confluent around the terminal hepatic venules, often extending to the portal tracts. Serum alanine aminotransferase activity was significantly elevated in guinea-pigs with severe liver damage. Hepatocytes in the damaged areas showed degenerative changes ranging from vacuolization to ballooning degeneration and necrosis. Inflammatory cells, predominantly lymphocytes, were often present in the areas of necrosis. The pathology of mild and severe liver injury in the guinea-pig closely resembles the spectrum of injury observed in non-fatal halothane hepatitis in man.