Detection of bicarbonate administration (milkshake) in Standardbred horses

Abstract

Total plasma carbon dioxide (TCO2) concentrations were measured in Standardbred horses to determine criteria to discriminate between normal horses and horses with excessive TCO2 concentrations on raceday. TCO2 concentrations from stabled horses were distributed normally with a mean of 30.2 mmol/L and a standard deviation of 1.2 (n = 192) while pre-race TCO2 concentrations were not normally distributed. The results indicate that about 50 horses per million are likely to have TCO2 concentrations greater than or equal to 35 mmol/L and that it is extremely unlikely that a normal horse would have a resting TCO2 concentration above 36 mmol/L. These values were associated with sensitivities of 67% and 59%, respectively, and with a specificity of 100%. TCO2 concentrations were relatively stable in blood samples stored at 4 degrees C for 4 days, whereas the TCO2 in specimens stored at room temperature (25 degrees C) and at ambient temperature (16-28 degrees C) declined progressively over 5 days. The accuracy and precision of the Beckman EL-ISE Auto Analyser were acceptable and within the manufacturers specified range. Paired specimens analysed using a Beckman EL-ISE Auto Analyser and a Kodak Dry Chemistry Analyser were not significantly different. However, the measurements made using the Kodak Dry Chemistry Analyser averaged 0.5 mmol/L higher than those analysed on the Beckman EL-ISE. The significance of these sources of variation in TCO2 concentration in relation to the testing of horses for 'milkshake' administration are discussed.

Isolation of bicarbonate from equine urine for isotope ratio mass spectrometry†

“…It is an easy, cheap and adequately accurate and reproducible method. The implementation of the isolation of TCO 2 from urine by acid release for an isotopic analysis as it is performed for the routine quantitative analysis of blood [5] is questionable, as the isotopic fractionation between the gaseous and aqueous phases may occur.…”

“…The administration of bicarbonate to a horse prior to a race is considered as doping offence, and a threshold for the total plasma concentration of CO 2 in equine blood has been set to 36 mmol/l. A higher concentration is regarded as evidence for the administration of bicarbonate [5].…”

Effect of omeprazole and ranitidine on total carbon dioxide concentration in horses subjected to a simulated race test

“…Since plasma [tCO 2 ] has been shown to be representative of plasma bicarbonate concentrations, the extent to which the horse is able to buffer the decrease in plasma pH that occurs with high-intensity exercise can also be shown [3][4][5][6][7][8]10,11 . During high-intensity exercise, the metabolic pathways used in muscle cells shift toward anaerobic glycolysis.…”

Evaluation of Ion Exclusion Chromatography as a Method for Determining the Total Carbon Dioxide (TCO2) Concentration in Equine Plasma

“…Firstly, the analysis of the ASE linearity set as samples after linearity was achieved. Though the EL-ISE ® system was supposedly able to analyze TCO 2 concentrations from 0 to 30 mM [7], it had difficulties analyzing samples spiked with the acetate IS. This was potentially due to the acetate ion acting as a buffer, thus inhibiting the proper release of CO 2 gas.…”

“…Several different ways of analyzing TCO 2 are available from a variety of vendors. For example, the Olympus system which uses an enzymatic method [11,12] for measuring bicarbonate or the Kodak Dry Chemistry Analyzer which utilizes potentiometric analysis had been used for analyzing equine plasma samples [7], though, there have had been reports of organic acids interfering with its analysis [13,14], similar to the EL-ISE ® [8]. As with the EL-ISE ® , these instruments utilize a principle of indirect measurement by converting the available TCO 2 into other forms, with the results determined from external calibration.…”