Since Kentucky regulators took over the administration of race-day Lasix in October of last year, scientists at the state's official testing laboratory say the change in regulation appears to be doing its job.
Dr. Rick Sams, director of the HFL Sport Science testing laboratory in Lexington, Ky., reports that his team has run the numbers on Lasix levels and found that violations related to the drug are much less common than they were before the state racing commission's veterinarians began administering it.
“If you go back a year ago, before the commission began doing these administrations, there was much wider variability,” he said. “We did a statistical analysis on the distribution of furosemide concentration before and after the commission veterinarians began treating the horses and we saw the same thing regardless of the [track and meet] comparisons we made—we saw a lower mean and a narrower distribution after the commission vets began doing the administrations.”
Urine samples are tested for the presence and the concentration of Lasix, according to Sams, both to ensure the drug was administered as reported in the program and to check whether the levels in the horse's system are appropriate to the threshold established by the state.
A concentration of Lasix above the established threshold would indicate that the horse received too much Lasix, received it too close to the race, or received it via intramuscular injection, which is not permitted.
Sams said employees of the racing commission's office have reported being asked to give the drug partially or completely via intramuscular rather than intravenous injection, or to give a greater volume of the drug than is permitted.
“I think it's quite clear that the specific requirements of the rule were not being met fairly widely [before the rule change],” he said.
Intramuscular administration results in a more gradual release of the active ingredients in furosemide. The drug works by blocking potassium and sodium ions from attaching in the kidney, which creates a diuretic effect.
Sams estimates the horse loses 10 to 20 liters of water as a result of Lasix administration, resulting in dilute urine that is easy to detect in the lab.
In the days before the state's veterinarians gave Lasix, trainers might have been inclined to give horses a larger dose of the drug. This doesn't tend to provide much of an advantage beyond a certain point, according to Sams, because eventually all the receptors in the kidney are blocked by the drug and the remainder is excreted in urine.
Giving a dose intramuscularly staggers the release of Lasix, however, so when the furosemide molecules drop off sodium and potassium receptors there are more in the system to replace them. Sams said he suspects the few trainers or veterinarians still inclined to cheat after the institution of state oversight may be giving their runners a supplemental intramuscular injection of Lasix after the state veterinarians have left the stall—and he can tell.
Horses with Lasix levels that are unusually high but below the legal threshold (sometimes by a matter of fractions of a microgram per milliliter) are not issued a violation, but Sams said he passes their sample numbers onto racing commission officials for monitoring.
“I will tell you that Dr. Scollay (Kentucky equine medical director Dr. Mary Scollay) sees these reports. She will take note of this finding and will probably let the stewards know,” said Sams.
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