POSTPRANDIAL SERUM BILE-ACID CONCENTRATIONS AND AMMONIA TOLERANCE IN MALTESE DOGS WITH AND WITHOUT HEPATIC VASCULAR ANOMALIES

Post-prandial serum bile acid concentrations were measured in 200 Malt ese dogs in an attempt to identify those with subclinical portosystemi c shunts. Five of these were later shown to have hepatic pathology or abnormal liver function. In the other 195 Maltese, bile acid concentra tions ranged from 1 to 362 mu mol.L(-1) (mean +/- SD, 70 +/- 50 mu mol .L(-1); median, 65.0 mu mol.L(-1)). Of these, 79% were above the refer ence range (0 to 31 mu mol.L(-1)) established from 23 mixed-breed cont rol dogs. It was therefore not possible to determine the prevalence of subclinical portosystemic shunts on the basis of bile acid determinat ions. Further investigation of liver function was performed to investi gate why bile acid concentrations were increased in these dogs. Rectal ammonia tolerance tests were normal in 102 of 106 Maltese tested and liver samples (11 dogs) and plasma biochemistry profiles (9 dogs) demo nstrated no significant hepatic disease or dysfunction. Of 2 Maltese w ith hyperammonaemia af ter administration of ammonium chloride, one ha d a large congenital portosystemic shunt that was confirmed at surgery . In the other there were no macroscopic portosystemic communications, but a liver biopsy showed histological changes consistent with micros copic portovascular dysplasia. Total serum bile acid concentrations we re consistently lower when assessed by highperformance liquid chromato graphy than by an enzymatic spectrophotometric method. This discrepanc y was substantially larger in Maltese than in control dogs, suggesting the presence of an additional reacting substance in the serum of Malt ese dogs.