Sample Handling’s Effects on Plasma CO2 Levels (AAEP 2012)

Researchers evaluated sample handling and storage time’s effects on CO2 concentrations in horse blood plasma.

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By its very nature the practice of “milkshaking,” or administering bicarbonate or other alkalinizing substances to racehorses as performance enhancers, can be tough to pinpoint—horses metabolize the substances quickly, and testing laboratories must look for elevated blood total carbon dioxide (CO2) concentrations as evidence. So to preserve an accurate snapshot of the horse’s blood CO2 levels at collection time, and ensure consistent test results, proper sample storage and handling are crucial.

Purdue University researchers recently evaluated sample handling and storage time’s effects on total CO2 concentrations in plasma. Stacy Tinkler, DVM, Dipl. ACVIM, clinical assistant professor of equine community practice in the university’s College of Veterinary Medicine, reported their results at the 2012 American Association of Equine Practitioners convention, held Dec. 1-5 in Anaheim, Calif.

Veterinarians and trainers believe mixtures of bicarbonate and/or other alkaline substances, administered to a horse shortly before he competes delays lactic acid buildup in a horse’s muscles, allowing them to run farther before tiring. Physicians consider it a moderate performance enhancer in human athletes performing short, intense exercise.

Tinkler explained that veterinarians can test for excess carbon dioxide in the blood before or after a race, depending on the particular track’s testing protocol; however, inconsistent sampling, processing, and storage methods commonly cause laboratories to underestimate total CO2. "This lab error could work in favor of those who may be administering alkalinizing agents to horses illegally because it might falsely lowers the total CO2 value below the detection limit, and some horses that have been given a ‘milkshake’ will compete, potentially lending them an unfair advantage over other horses," she said

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Written by:

Erica Larson, former news editor for The Horse, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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