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Why Do Race Horses Have to Pee so Bad? Fact Fiction & Causes

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If you have ever been to the racetrack, you’ve likely noticed the horses pee an awful lot. Is there a reason racehorses pee so much? I thought I knew the answer, but I decided to do some research, and I provide my findings here.

Racehorses have to pee so bad because they are injected with the diuretic drug Lasix shortly before a race. Lasix draws fluids into the horse’s bladder, which results in the discharge of several gallons of urine within an hour of injection.

Lasix is the main reason for excessive peeing by a racehorse but not the only one. Let’s dive deeper and learn more about this exciting topic.

Horses typically pee 2.5 gallons of urine a day.

Horses should urinate approximately 0.3 fluid ounces per pound of body weight per day. For a typical sized horse, this translates to about two and a half gallons daily.

However, the amount of urine varies depending on factors such as the amount of fluid intake, age, weather, feed, and size of the horse. Urine in a healthy horse should be clear with a yellow tint of color and have a minimal odor. A horse should pee easily and in a steady stream.


Urination is a vital bodily function. It eliminates waste from the body and plays a role in blood pressure and electrolyte balance. If you have a horse that isn’t producing urine or is having difficulty urinating, you should contact a veterinarian immediately. Some causes of urinary retention in a horse are life-threatening.

Horse urine should be pale yellow.

Urine Indication
Pale in color Normal indicates good hydration
Dark yellow Evidence of concentrated urine. Could be caused by a lack of water intake or excessive sweating.
Orange-red If your horse is passing orange urine contact your veterinarian, however, if the urine turns orange on the ground, this is a normal reaction to the environment.
Cloudy Diet can cause cloudiness and shouldn’t be a cause for concern. As the bladder empties, excess calcium is released. Horses fed Alfalfa often display cloudy urine.
Smelly Urine’s odor is caused when a horse is fed more protein than their body needs. The excessive protein converts to nitrogen in the form of smelly ammonia. 
Increased frequency and decreased volume sometimes bloodyDribbling urine with spotty bleeding is a symptom of urinary stones in the kidneys or bladder. It is not a common occurrence.
Infrequent or uncomfortable This is a sign of urinary infection. In horses, it can have serious adverse consequences. Contact a veterinarian.
Very dark in color Dark urine can be the result of muscle damage or dehydration. If the urine is very dark and foamy, it is a classic sign of a horse “tying up.” Contact a veterinarian.

Lasix causes horses to pee.

Lasix is given to horses to prevent respiratory bleeding caused by physical exertion.  During a race, a horse is pumping vast amounts of blood into the vessels surrounding their lungs.

The pressure created by air entering the lungs, and blood pumping through blood vessels is forceful enough to burst capillaries. Once the barrier is broken blood enters the lungs and results in blood exiting the horses’ nostrils.  

The medical term associated with this phenomenon is referred to as exercise-induced pulmonary hemorrhage (EIPH). If the condition becomes chronic it will lead to decreased lung capacity, cause inflammation, or in rare cases be terminal.

It is estimated that approximately 90 percent of racehorses experience some degree of bleeding, although not all will result in bleeding from the nose.

Horse trainers often abuse Lasix.

Lasix can be abused on the race track when used not to control bleeding but to force a horse to pee. Trainers are always looking to give their horses an edge, and they believe an injection of Lasix gives their horse advantage.

Lasix causes a horse to release fluids, resulting in weight loss. To reduce the weight a horse carries during a race; trainers inject them with Lasix. It is estimated that a horse can drop 10 to 15 pounds of fluid within an hour after receiving a dose of Lasix. To find out how much weight a racehorse loses during a race, read our article.

Some racetracks are phasing out Lasix.

Horses that run with Lasix are noted on daily racing forms. These forms are used by the betting public to help them decide which horses to bet. The administration of Lasix is a considered factor by gamblers, so it logically flows that Lasix is affecting a horses’ racing ability.

In 2020 a coalition of major race tracks will start phasing out the use of Lasix on race day. The horse deaths at Santa Anita sparked the restriction. The first phase of the phase-out will be the restriction that no two-year-old racers can be treated with Lasix twenty-four hours before their race. Click the link to read an article we wrote about racehorse deaths.

The second phase will go into effect in 2021 and extend the ban to all horses running in any stakes race on the self-restricting tracks. Some of the more high profile tracks in the coalition are Churchill Downs, Pimlico, and Belmont.

If you are interested in learning about stakes races, you can read our article here. The American Quarter Horse Association (AQHA), is researching Lasix to determine if they are going to limit or ban its use in future AQHA horse show events.

Racehorses don’t pee more than other horses.


When you’re at the races and see large numbers of racehorses urinating, it makes you wonder if they pee more than any other horses.

Regular horses and racehorse pee the same amount. The difference is the use of Lasix in racehorses which causes them to pee excessively. Lasix use can be found in equine events other than racing.

Horses have large bladders

A horse’s bladder is big enough to hold three to four quarts of urine. A horse can develop stones in their bladders. The bladder stones are calcium concentrates.

The most common sign that a horse has bladder stones is blood in the urine after exercise. Watch your horse for apparent signs of strain, and he may display symptoms associated with colic. Bladder stones are more likely in males because they have a longer urinary tract.

Bladder stones often are the result of infected cells. The cells are covered in layers mineral deposits to the extent they form into a stone-like object. Diet plays a role in the formation of bladder stones.

If you suspect your horse has bladder stones call your veterinarian to confirm the diagnosis. Diagnosis is made by endoscopy or ultrasound. To treat a horse with a severe case of bladder stones requires surgery.

Remember, prevention is the best medicine. Keep your horse well hydrated, make sure he drinks a proper amount of water for the conditions he is kept. If your horse doesn’t drink the appropriate amount, try adding a supplement to the water to make it more inviting. Hydration is key to a healthy horse.

What does “pee like a Russian racehorse” mean?

Growing up with three brothers I often heard the phrase “pee like a Russian racehorse.” I wasn’t ever sure if they meant, Russian or rushing racehorse, but regardless I decided to find out more about this phrase.

Racehorses are nervous before a race and act as if they are in a rush. The horses are paraded in front of the grandstands and led into the paddock for saddling. As the racehorses nervously move in front of the spectators, they pee, often and a lot. Russian racehorse makes no sense.

Racehorse emptying their bladders right before a race became more prevalent as the use of Lasix increased. Thus it’s easy to take the logical step to a person describing an urgent need to urine as “I have to pee like a rushing racehorse.”

Steroid use is banned in horseracing.

The following medications are banned at most horse racing tracks: anabolic steroids, peptide hormones, and growth factors, beta-2 agonists, hormone and metabolic modulators, and certain diuretics.

Performance-enhancing drugs are a hot topic, in light of the rash of deaths at Santa Anita. The people of the horse racing industry are looking to take steps to decrease the number of horse deaths. However, there is no one governing body that has drug enforcement power over every U.S. track.

Guidelines have been established by the Racing Medication and Testing Consortium (RMTC) for the United States.  The guidelines address medication rules, penalties, and testing. Additionally, RMTC created a controlled substance list limiting the administration of Lasix.

You can read more about the Racing Medication and Testing Consortium on their website. The American Quarter Horse Association website provides a list of drugs banned for use on horses that compete in quarter horse races. You can access their website by clicking the above link.

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