Peer-reviewed veterinary case report
How blood ammonia and bile acid tests find liver shunts in dogs
By van Straten, G et al.·Published in Veterinary journal (London, England : 1997)·2015·Department of Clinical Sciences of Companion Animals, Netherlands·View original on PubMed →
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Original publication title: Diagnostic value of the rectal ammonia tolerance test, fasting plasma ammonia and fasting plasma bile acids for canine portosystemic shunting.
- Species:
- dog
Plain-English summary
A group of dogs suspected of having portosystemic shunting (PSS), a condition that can cause serious liver problems, underwent several tests to diagnose the issue. The ammonia tolerance test and fasting bile acids test were found to be very effective, with nearly all dogs showing abnormal results if they had PSS. In fact, if a dog had normal results on these tests, it was unlikely they had PSS. For dogs that had surgery to correct PSS, elevated fasting ammonia levels were a strong indicator of the condition. These findings can help vets diagnose PSS more accurately and quickly.
People also search for: dog portosystemic shunting symptoms · dog liver disease tests · dog ammonia tolerance test
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.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/25959128/