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Effects of dietary changes on gastric emptying of horses by means of the 13C-octanoic acid breath test

Kristen Kastner and Allen Roussell

Dept. Large Animal Medicine & Surgery, Texas A&M University, College Station, TX


Objective:  The objective of this study was to utilize the 13C-octanoic acid breath test for detection of changes in the rate of solid phase gastric emptying in horses, induced by alterations in test meal composition.

Animals:  Four adult French native-breed horses, with initial bodyweights between 400 and 440 kg, were used in the study.

Procedure:  After an overnight fast, the horses received a test meal of either low starch, corn-based high starch, or oat-based high starch labeled with 13C-octanoic acid.  Each horse was given the three test meals on three separate occasions.  For each test, expiratory breath samples were collected in duplicate at 1 hour, 15 minutes and immediately before ingestion of the test meal and at frequent intervals thereafter for 8 hours. Analysis of breath 13CO2:12CO2 ratio was conducted by continuous flow isotope ratio mass spectrometry.  Power regression was used to determine the gastric emptying coefficient, the gastric half-emptying time (t1/2) and duration of the lag phase (tlag).

Results: Pending data analysis by IRMS.

Clinical relevance:  Either a slowing or acceleration of gastric emptying may be important in inducing colic, which is known to be more frequent following a change in diet.