Using Of Lasix In Horse Racing

Lasix, also known as furosemide and described as an anti-bleeding medication, is used by veterinarians in horse racing to prevent respiratory bleeding in horses running at high speed. Blood entering the lungs during high physical activity can cause a pulmonary hemorrhage and result in death. 

A galloping horse inhales deeply when their legs come together beneath them and exhales powerfully when their legs land outstretched. The animal’s robust heart and contractile spleen work together, pumping vast amounts of blood into the blood vessels of the lungs.

The volume and pressure of both the blood and air entering and exiting is so forceful that it can break through the thin blood-gas barrier of the alveoli, causing blood to enter the lungs. It’s estimated that around 90 percent of racehorses experience at least some amount of bleeding. And in about 3 to 5 percent of horses, lung bleeding causes nose bleeds. In most cases, a veterinarian’s endoscopic examination confirms bleeding.

Horses also tend to bleed more the more they run. They recover, but only after suffering permanent lung damage. Repeated bleeding is thought to cause inflammation, tissue damage and decreased lung capacity. In rare instances, it’s fatal.

What are Lasix’s other uses?

Lasix also works as a diuretic that causes horses to urinate before a race and lose 20 to 30 pounds of fluid, thus increasing the ability of the horse to run faster.  

When is Lasix used? 

Horses are administered the drug on race days, usually four hours before the race. 

Does Lasix improve performance during the race?

There are varying opinions. Some might suggest the effects are minimal at best on a horse’s performance, but the school of thought that is generally accepted is that a reduction in bleeding and blood entering the lungs will obviously allow a horse to breathe better during a race and thus run better. The fluid loss that accompanies the administration of Lasix also can help a horse run faster. 

How often is Lasix used?

It is routinely widespread at North American race tracks, with nearly all horses and trainers using it. Of 119 horses (counting also-eligibles) drawn into 11 races at Keeneland this past Saturday, only two were not listed as using Lasix, meaning 98.3 percent were using it.

Is Lasix used worldwide?

Outside of North America, the medication is widely banned on race days. 

What effect could a ban on Lasix have on horse racing?

It has been proven elsewhere that horses can run without Lasix, but its use is so widespread in North America that an immediate ban — rather than the ability to start with 2-year-olds only or gradually wean older horses off it — could be highly problematic and potentially carry some frightening health risks. A nightmare scenario would be a horse bleeding into the lungs to the point of becoming incapacitated during a race. 

Who Administers Lasix?

At Kentucky tracks, only veterinarians with the Kentucky Horse Racing Commission are allowed to give a racehorse the furosemide injection on race days. Before 2012, private veterinarians were allowed to give the shot.  

Is Lasix used in humans?

Furosemide is used to treat blood pressure in people. It also works to reduce extra fluid in the body. The fluid buildup could be caused by heart failure, kidney disease and liver disease, for example. 

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