3-ALPHA-HYDROXYLATED BILE-ACID PROFILES IN CLINICALLY NORMAL CATS, CATS WITH SEVERE HEPATIC LIPIDOSIS, AND CATS WITH COMPLETE EXTRAHEPATIC BILE-DUCT OCCLUSION

Concentrations of 3alpha-hydroxylated bile acids were measured in seru m and urine of clinically normal (healthy) cats (n = 6), cats with sev ere hepatic lipidosis (n = 9), and cats with complete bile duct occlus ion (n = 4). Bile acid concentrations were measured by use of a gradie nt flow high-performance liquid chromatography procedure with an aceto nitrile and ammonium phosphate mobile phase and an in-line postanalyti c column containing 3alpha-hydroxysteroid dehydrogenase and a fluoresc ence detector. Specific identification of all bile acid peaks was not completed; unidentified moieties were represented in terms of their el ution time (in minutes). Significant differences in serum and urine bi le acid concentrations, quantitative and proportional, were determined among groups of cats. Cats with hepatic lipidosis and bile duct occlu sion had significantly (p greater-than-or-equal-to 0.05) greater total serum and urine bile acids concentrations than did healthy cats. The proportion of hydrophobic bile acids in serum, those eluting at greate r-than-or-equal-to 400 minutes, was 1.9% for healthy cats, 3.3% for ca ts with lipidosis, and 5.4% for bile duct-obstructed cats. Both groups of ill cats had a broader spectrum of unidentified late-eluting serum bile acids than did healthy cats; the largest spectrum developed in b ile duct-occluded cats. The trihydroxy-to-dihydroxy serum bile acids r atio was 8.8:1 for healthy cats; 24.1:1 for cats with lipidosis; and 2 0:1 for cats with bile duct obstruction. There was a paucity of glycin e-conjugated bile acids in all cats and small quantities of secondary bile acids in ill cats. A significantly (p < 0.05) smaller proportion of unconjugated primary bile acids was detected in sera from ill cats. Serum taurolithocholic acid was detected only in small quantities in cats of each group. There was significantly increased quantity, but lo wer proportion, of trihydroxy-cholestanoic acid in serum from ill cats , compared with healthy cats. A significantly (p < 0.05) greater propo rtional amount of unidentified moieties eluting at 130 and 277 minutes was detected in urine of cats with hepatic lipidosis; we believe that the unidentified moiety eluting at 277 minutes is taurocholic acid. L arge proportional amounts of taurocholic and cholic acids were detecte d in urine of all cats, but ill cats had significantly (P < 0.05) grea ter quantities (quantitatively and proportional). Ill cats had signifi cantly (P < 0.05) more taurocholic than cholic acid in urine. Because taurine is an essential amino acid for cats and is a necessary daily d ietary constituent, large urinary losses of taurine in conjugated bile acids may further compromise the health of anorectic cats with severe hepatic lipidosis.