Why do they give Lasix to racehorses?

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Fah-Q

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I'm an amateur gambler and I try to make to the horse races a few times a year. My question is why do they give horses Lasix? The trainers and the track must declare if their horse is on Lasix and even have to declare whether this is the first time the horse has been on Lasix. My father's family used to own racehorses and I asked him and he told me that it was because they will "bleed into their lungs" without the Lasix. I am assuming that he is referring to pulmonary edema. So what's the mechanism? Lasix is widely used on racehorses and it gave rise to the phrase "I gotta piss like a racehorse." Anyways, I figured someone out there must know the exact reason they use Lasix and why it might enhance performance.

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i found this on a web site:

Lasix

Lasix is one of the most frequently used medicines and has been around for many decades. Lasix stimulates kidneys to produce more urine, as a result it reduces the amount of free water in the body. Along with increase in urine volume, Lasix causes loss of Sodium and Potassium in the urine.

Lasix is used in following situations:

Fluid overload in the body such as in heart failure or kidney failure
To establish a constant urine flow to prevent potential kidney damage from Cisplatinum
Urgent treatment of Hypertension
Lasix is available in Intravenous as well as oral tablets. Intravenous method of administration is used to achieve an urgent effect. Oral tablets are used for maintaining the effect of medicine. Oral tablets of Lasix are used once or twice a day.
 
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The stuff about pulmonary edema makes sense, since Lasix is also used for this in humans. I'm assuming they shoot the horses up pretty close to racetime, since they don't want them to become volume depleted, so the mechanism probably has more to do with vasodilation rather than diuresis.

On a related note, I remember sometime back in the 80's there was this horse (can't remember the name) that won the Kentucky Derby and Preakness on Lasix. When he went for the Triple Crown at the Belmont Stakes, they wouldn't let the trainers give him the drug and he finished somewhere back in the pack. I guess Lasix is the anabolic steroid of the thoroughbred world.
 
Lasix makes them pee out a lot of water, thus they lose water weight. The less weight they're carrying, the faster they run.

This works best the first time they're given the lasix, so that's why you want to bet on a "first time lasix" horse. It should say that in the race guide.

Pee like a racehorse.
 
•••quote:•••Originally posted by rubyness:
•Lasix makes them pee out a lot of water, thus they lose water weight. The less weight they're carrying, the faster they run.

This works best the first time they're given the lasix, so that's why you want to bet on a "first time lasix" horse. It should say that in the race guide.

Pee like a racehorse.•••••Its seems to me that would only dehydrate them and cause cramping. Going back to the pulmonary edema theory, perhaps it occurs during the race and decreases the diffusion of oxygen? Just guessing here. But if they have pulmonary edema during the race then it is probably cardiogenic. So why can the left side of the heart deliver enough blood to the muscles to run but can't pump efficiently enough to pull the fluid out of the lungs? Any other ideas?
 
I used to run horses at the track and this is one of my favorite subjects! (um, not Lasix, but racing.) Yes, pee like a racehorse does come from Lasix induced urination! When young horses are first run hard in a race, they are carefully watched to see if they "bleed out" the nose. Sometimes it doesn't happen for a couple of races or so. Sometimes a trainer tries it if the horse seems to be having trouble breathing but is not obviously bleeding. The Lasix prevents this, I assume from vasodilation as previously mentioned. No one ever can guess how well a first-time horse on Lasix will run. Invariably, they will run much, much better. Duh, they can breathe and they aren't gurgling blood up from their lungs! Of course, first-timers are usually well bet on and their odds usually go down because of it. BTW, most horses at the track are on the stuff and it's listed in the program. I love to talk about the ponies! Have broken many bones on them though... <img border="0" title="" alt="[Frown]" src="frown.gif" />
 
hey lamyers - i can relate. used to be an exercise rider!
 
Don't you miss it? When I'm a physician, I'm going to have my own! I was in the best shape then!
 
why do the horses bleed from their lungs when they race?
 
Is that where the term, "I gotta pee like a racehorse" comes from? :)

PB
 
Yep, that's where the phrase came from. I'm not sure physiologically why they bleed. I'll have to look that one up. My boss used to say that they ran so hard they would break vessels in the lungs, but who knows?
 
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