Evaluation of a semiquantitative SNAP test for measurement of bile acids in dogs

Background. Serum bile acids (SBA) are used as a routine screening tool of liver function in dogs. Serum samples are usually shipped to a referral laboratory for quantitative analysis with an enzymatic chemistry analyzer. The canine SNAP Bile Acids Test (SNAP-BAT) provides an immediate, semi-quantitative measurement of bile acid concentrations in-house. With the SNAP-BAT, bile acids concentrations of 5-30 µmol/L are quantified, and results outside of that range are classified as <5 or >30 µmol/L. Agreement of the SNAP-BAT with the enzymatic method has not been extensively investigated. Objectives. The purposes of this prospective clinical study were to assess the precision of the SNAP-BAT and determine agreement of SNAP-BAT with results from an in-house chemistry analyzer. Methods. After verifying intra-assay precision of the SNAP-BAT, a prospective analysis was performed using blood samples collected from 56 dogs suspected to have liver disease. Each sample was analyzed with an enzymatic, in-house chemistry analyzer and the SNAP-BAT. Agreement between the two methods was statistically assessed using the κ index of agreement. Results. Intra-assay variability was minimal. The κ index for agreement between the SNAP-BAT and routine chemistry analyzer was between 0.752 and 0.819, indicating substantial to near perfect agreement. Conclusions. The SNAP-BAT is a highly accurate, semi-quantitative test that yields immediate results, and has very little intra-assay variability, particularly for results >30 µmol/L.