Use of the C-13-octanoic acid breath test for assessment of solid-phase gastric emptying in dogs

Objective-To assess the C-13-octanoic acid breath test for determining gast ric emptying in dogs. Animals-6 healthy adult dogs. Procedure-Food was withheld for 12 hours before each test. Expired air was collected 30 minutes and immediately before each test and at frequent inter vals thereafter for 6 hours. Concentration of (CO2)-C-13 in expired air was determined by use of continuous-flow isotope-ratio mass spectrometry. Basa l concentration of (CO2)-C-13 was measured in dogs that were not fed a test meal. Effects of the standard unlabeled test meal on basal concentration o f (CO2)-C-13 were then assessed. The optimum dose of substrate was determin ed by measuring (CO2)-C-13 concentration after ingestion of the standard te st meal containing 50 or 100 mg of C-13-octanoic acid, whereas effect of en ergy density of the test meal on gastric emptying was determined after inge stion of the standard or high-energy labeled test meal. Gastric emptying co efficient (GEC), time to peak (CO2)-C-13 concentration and half-dose recove ry time (t(1/2)) were calculated. Results-Basal concentration of (CO2)-C-13 in expired air was not significan tly affected by ingestion of the unlabeled test meal. However, (CO2)-C-13 c oncentration significantly increased in a dose-dependent manner after inges tion of the labeled meal. Gastric emptying coefficient, t(max), and t(1/2) were significantly different between dogs fed the standard and high-energy test meals, indicating that ingestion of a high-energy meal delays gastric emptying. Conclusions and Clinical Relevance-The C-13-octanoic acid breath test may b e a useful noninvasive and nonradioactive method for assessment of gastric emptying in dogs.