The Harmful Effects Of Lasix

Last Updated on April 4, 2022 by Allison Price

You are probably familiar with the conflicts surrounding Lasix or furosemide if you are involved in race horses.

Furosemide was originally created to treat bleeding lungs in race horses. But many also view furosemide as a performance-enhancer, helping race horses perform better during a race.

Is Lasix a performance-enhancer? How does furosemide help race horses? What are the other treatment options for horses suffering from bleeding lungs? We will explore the harmful effects of Lasix and other options for treating EIPH in this article.

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Lasix History

Lasix was originally developed as a treatment to treat bleeding lungs. Lasix can be administered before horses are raced to reduce the risk of bleeding. Learn more about bleeding lungs by reading our How to treat bleeding lungs post.

However, opinions differ on whether Lasix helps to prevent bleeding during races. However, Lasix is used by a large number of race horses. According to Bill Heller’s book, Run, Baby, Run, 92% of all race horses used Lasix in 2001.

Lasix has been shown to be effective in preventing horses from bleeding their lungs. But that doesn’t diminish the harmful effects associated with Lasix, along with the controversy over whether Lasix acts as a performance-enhancing drug.


Lasix can be administered intravenously to an individual before they race. However, it has side effects that are similar to diuretics. It can also cause electrolyte imbalances and dehydration, as well as decreased blood calcium levels.

Effects Of Lasix

Lasix can cause horses to lose between 10 and 15 liters of urine within an hour. Many race horses are prohibited from drinking water for the first four hours before a race. This can lead to a loss of 10-20 pounds.

Here is the problem. Lasix horses can lose 20 pounds just before a race. Does that make them handicapping other Lasix horses?

The current permissible Lasix dosage before a race is 500mg. Some race horse trainers remain skeptical.

Kiaran McLaughlin, trainer, is one of the signatories to a proposal that would eliminate Lasix from races. He says it’s “very interesting.” We surveyed every horse, after they ran, and most horses, after they worked, for two years. I can tell you that less than 5% of horses we ran without Lasix ever bled.

Find a Better Alternative

Bleeding lungs can still happen in some race horses. What does this mean for treatment of bleeding?

Race Today(tm), from Equine is a great alternative. Race Today(tm), unlike other coagulants, doesn’t overdose race horses. Race Today(tm), which is a feed supplement, was developed and tested by an equine veterinarian. It contains vitamins and minerals that are essential for horse health. It is designed to strengthen the lungs and prevent bleeding.

Race Today(tm), a daily feed supplement, is great for horses. It is great for general lung health and can also eliminate symptoms of EIPH. Although it can be used in conjunction with lasix, most horses don’t need it.

There are many questions surrounding the negative effects of Lasix, and whether it can increase performance during races. However, there are still other options available to help bleeders.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!