Adequate diet prevents hepatic coma in dogs with Eck fistulas

The conventional animal model of human portal systemic encephalopathy is the dog with Eck fistula. Dogs fed standard dog chow after Eck fistula manifest anorexia, weight loss, hepatic atrophy and encephalopathy. This study was done to determine the natural history of dogs undergoing Eck fistulas when adequate nutrition is maintained with a palatable diet. Twenty-four mongrel dogs were divided into four groups--Eck fistula fed standard dry dog chow (EF-SC) (n equals nine); sham operated fed standard chow (SO-SC) (n equals five); Eck fistula fed a liquid (Isocal) diet (EF-LD), LD), and sham operated fed a liquid diet (SO-LD) (n equals five). Dogs were sacrificed when they had clinical signs of encephalopathy or up to 120 days after operation. EF-SC dogs had a daily caloric intake approximately 40 per cent of that of the other groups. Two EF-SC dogs died of sepsis within two weeks of the operation, the other seven became encephalopathic between 46 and 91 days (a mean of 63.6 +/- 15.6). No other dogs had signs of neurologic deterioration. EF-SC dogs lost 19 +/- 9 per cent body weight and the serum albumin level decreased 14.5 per cent while the other groups maintained body weight and serum albumin levels. Both EF-SC and EF-LD groups had decreased liver weight to body weight ratios (LW X 100/BW) compared with sham operated upon dogs reflecting hepatic atrophy (1.97 +/- 0.7 and 2.2 +/- 0.23 versus 3.04 +/- 0.85 and 3.48 +/- 0.44). Results of histologic examination of the liver revealed hepatocyte atrophy, deglycogenation and lipid accumulation in EF dogs. We conclude from these data that providing dogs with Eck fistula a palatable diet prevents weight loss and malnutrition, but not hepatic atrophy. The lack of neurologic signs in well nourished dogs suggests to us that data concerning hepatic coma from the standard Eck fistula model should be interpreted with extreme caution.