title: Diagnostic value of the rectal ammonia tolerance test, fasting plasma ammonia and fasting plasma bile acids for canine portosystemic shunting.
abstract: Portosystemic shunting (PSS) often results in hyperammonaemia and, consequently, hepatic encephalopathy. This retrospective study evaluated the sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively) and other test performance metrics for the ammonia tolerance test (ATT), serum fasting bile acids (FBA), serum fasting ammonia concentration (FA), and combinations of these tests for their association with PSS in dogs. Medical records of 271 dogs suspect for PSS (symptomatic group) and 53 dogs returning for evaluation after surgical closure of a congenital PSS (CPSS post-surgical control group) were analysed. In the symptomatic group, ATT at 40 min (T40), and the FBA had the highest sensitivity (100% and 98%, respectively) and NPV (100% and 96%, respectively) for PSS. The combination of increased FBA and FA had the highest specificity (97%), with a PPV of 97%, and a positive likelihood ratio of 29. In the CPSS post-surgical control group, the specificity and PPV of FA and the combination of increased FBA/FA were both 100%. In purebred populations, the NPV of all tests was 100%. Consequently, PSS would be ruled out in a symptomatic dog with normal FBA or ATT (T40) and would be highly probable when both FBA and FA are increased. Increased FA was conclusive for PSS in dogs evaluated for post-surgical closure of a CPSS. FBA was the most suitable test for screening purposes.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. Electronic address: g.vanstraten@uu.nl.
authors.forename: G
authors.initials: G
authors.lastname: van Straten
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Spee
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Rothuizen
authors.affiliation: 'Hachaklait', Mutual Society for Veterinary Services, P.O.B. 3039, Caesarea Industrial Park 38900, Israel; Koret School of Veterinary Medicine, Faculty of Agriculture, Hebrew University of Jerusalem, P.O.B. 12, Rechovot 76100, Israel.
authors.forename: M
authors.initials: M
authors.lastname: van Straten
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: R P
authors.initials: RP
authors.lastname: Favier
mesh_terms: D000285:Administration, Rectal; D000641:Ammonia / Q000008:administration & dosage / Q000097:blood*; D000818:Animals; D001165:Arteriovenous Malformations / Q000175:diagnosis / Q000662:veterinary*; D001647:Bile Acids and Salts / Q000097:blood*; D004283:Dog Diseases / Q000097:blood* / Q000175:diagnosis / Q000378:metabolism; D004285:Dogs; D011168:Portal System / Q000002:abnormalities*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D001647:Bile Acids and Salts; D000641:Ammonia
keywords: Ammonia tolerance test; Congenital portosystemic shunt; Fasting ammonia concentrations; Fasting bile acids; Predictive values