The Science of Furosemide

[Whirlaway]

After reading the article posted by Patuxet, “Riding the Pine”, I became interested in how and why Lasix works and how it effects racetrack performance. It all starter here: http://veterinarynews.dvm360.com/dvm/ar ... &&pageID=2 I read the article, followed the references and found the study by Gross, Morley and Hinchcliff, titled: Effect of furosemide on performance of Thoroughbreds racing in the United States and Canada.


An excerpt from the study:

Furosemide was administered to 16,761 horses. Horses that received furosemide raced faster, earned more money, and were more likely to win or finish in the top 3 positions than horses that did not. Horses receiving furosemide had an estimated 6-furlong race time that ranged from 0.56 seconds to 1.09 seconds less than that for horses not receiving furosemide, a difference equivalent to 3 to 5.5 lengths.


One full second difference - I knew it was the "juice" but I didn't know to what extent. The study details types and sex of horses benefiting most from the drug. Found two more studies led by Kenneth W. Hinchcliff: Efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses and Association between exercise-induced pulmonary hemorrhage and performance in Thoroughbred racehorses.

Hinchcliff is pretty sharp and interesting how he poses questions in one study and answers them in the next. He tells us Lasix works, but they don’t know how it works.

[ratherrapid]

he ends the post

horses bleed, furmoside works.

all we need to know probably.

If u read the Safrican study---it's flawed because so few horses actually race without lasix. If lasix continues to be a USA issue there should be a usa study. there's zero performance advantage if all horses race on lasix. i've had horses win without the drug.

[Whirlaway]

he ends the post

horses bleed, furmoside works.

all we need to know probably.

If u read the Safrican study---it's flawed because so few horses actually race without lasix. If lasix continues to be a USA issue there should be a usa study. there's zero performance advantage if all horses race on lasix. i've had horses win without the drug.

Wish it was that easy.

I’ve done some additional reading on the subject matter and found it interesting that supporters of the drug and its use cite studies supporting their position while ignoring studies proving otherwise.
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With respect to flaws in the South African study the author writes, “Horses were enrolled without knowledge of whether they had previously had EIPH, with the exception that horses with a history of epistasis during racing or training that had been document by a veterinarian or steward employed by the NHRA were excluded.” In the final paragraph he writes, “Although racing and training conditions in other parts of the world do differ from those in South Africa in minor respects . . . we believe the results of the present study are relevant to horses racing worldwide.” How the data relates to horses in the United States, in the 199 study he writes, “Because of the large study population and resulting statistical power, the magnitude and consistency of the observed effect, and the fact that the study population was likely representative of the population of Thoroughbred horses racing in the United States and Canada, we believe that our results present clear and unequivocal evidence of an association between use of furosemide and superior performance in Thoroughbred race horses.”

What I found particularly compelling, the best scientists in the world do not understand the mechanism by which the drug works. “These considerations highlight the inadequacy of our knowledge of the dynamics of pulmonary hemorrhage in horses during and after exercise.” Scientists need to keep at it and understand how the drug works then create a treatment that reduces EPIH without enhancing performance. I think they can do it.

Until then, I’ll keep in mind how Lasix and nasal strips can alter racetrack performance, keeping a keen eye out for those horses the study proves it benefits most. An additional tidbit of information for those interested. “Furosemide is the drug most widely used to prevent EIPH in racehorses and is administered on the day of racing to > 92% of Thoroughbred racehorses in North America (approx. 400,000 doses/y).”