Study Suggests Furosemide Creates Lingering Sodium Imbalance Horses Struggle To Correct

by | 11.14.2017 | 1:14pm

Few racehorses compete without furosemide, a diuretic known commercially as Lasix, to reduce bleeding in the lungs, or exercise-induced pulmonary hemorrhage (EIPH). Horsemen and armchair veterinarians alike have questioned whether horses suffer a long-term impact from repeated dosing of furosemide. Furosemide causes horses to lose sodium, and they might not be able to make up that deficit by just licking a salt block. Sodium is essential for proper nerve function, so a sodium deficiency might decrease performance.

Renowned emeritus professor Dr. Katherine Houpt and her colleague Dr. Pamela Perry at Cornell University studied how furosemide affects the normal water and salt balance of horses who receive the drug chronically.

Houpt and her team used a herd of ponies at Cornell for the study, as the specially-outfitted urine collection stalls available for the research were too small to accommodate a Thoroughbred. The ponies were administered furosemide daily for three weeks. Researchers measured the ponies' water and sodium losses caused by the furosemide and the ponies' water and salt intake as they strived to replace those losses. The team took the same measurements for three weeks prior to furosemide administration to establish a baseline.

Houpt's team found furosemide caused an acute increase in salt and water intake, and the salt consumption persisted for the three weeks of the study, reaching a peak at day 10.

“Despite the increase in sodium chloride intake, four of the six ponies took in less sodium than they excreted in the urine,” Houpt reported. “This indicates that horses do not accommodate behaviorally to the physiological effects of the drug for at least three weeks.”

In other words, the ponies were unable to adjust their sodium balance to normal by just licking a salt block.

The ponies in the study led a sedentary life, and the study was performed in cool weather, so they didn't lose water and sodium via sweat. But Houpt is concerned that racehorses, which sweat during exercise, might be drawing sodium from their bodies if they cannot make up the deficit by licking a salt block.

“Sodium has to go into the cells for the nerves to fire,” Houpt said. “So if you've got low enough sodium, you would have problems. … you probably would see poor performance in these horses if they didn't make up for their salt loss.”

The study also showed that furosemide causes salt craving, so in some horses its administration might defeat its intended use, which is to reduce blood pressure so blood vessels in the lungs don't burst during exercise.

“If the horse has a greater blood volume because he's eaten more salt, then he may have higher blood pressure and that means he's more likely to bleed, so it could become a vicious circle,” Houpt said.

The obvious solution is to stop administering furosemide to racehorses, Houpt said. In the meantime, she suggested horses be offered salt to encourage them to correct the imbalance as much as possible, but the method of salt delivery could make a big difference.

“Make sure that they always have a block of salt,” Houpt said. “The advantage of the block of salt is that the horse will self-regulate, whereas if you mix it in his feed, he needs the calories, so he's going to [consume the salt] whether he needs it or not. So, it's better to have it available to him, and certainly available to him as soon as he comes off the racetrack, so that he can make up for the deficit he acquired when they gave him Lasix.”

Houpt acknowledged her study has been criticized, mainly because it was done with ponies instead of exercising Thoroughbreds, and because the animals received furosemide daily. She agreed that further study should be conducted with Thoroughbred racehorses under typical management and receiving furosemide only when they work out or race.

“Care must be taken in performing horses that they have access to salt and water,” the report concluded. “The horse will consume more salt, but will not be able to meet their acute needs while performing. Conversely, salt access should probably be restricted when the goals is to lower blood pressure or reduce edema. The long-term consequences to the horse's performance and health should also be investigated.”

One focus of the work performed by Dr. Gary Potter, a consulting nutritionist and professor emeritus of equine science at Texas A & M University, was the best method of salt intake in horses. Potter now advises trainers of performance horses through his Potter Enterprises.

“There is a tremendous increase in the need for electrolytes in racehorses and performance horses due to both furosemide treatment (in some) and sweating (by all),” he said. “Trying to put enough salt in mixed feed to offset those loses is counterproductive because, when feed contains much more than 0.5 percent salt, horses tend to back off on consumption—which is the last thing you want in a racehorse or performance horse.”

Potter advises trainers to add 0.5 percent salt to the feed portion of the horse's diet, and offer an additional three ounces of loose salt daily — not mixed in the feed — during warmer weather to compensate for sodium lost in sweat.

“Horses in training, even in cooler/colder weather, will need some supplemental salt—one to two ounces daily,” he added. “If horses are fed salt in their stalls, it is much more workable to feed loose salt for two reasons: 1) the allocation and consumption of salt can be accurately managed and monitored, and 2) salt consumption due to salt craving can be prevented. Given free-choice access to salt blocks for horses in stalls frequently results in excessive salt consumption, excessive water consumption, wet, messy stalls, etc.”

Potter said Houpt's paper and other work points to an issue that often is mismanaged in performance horses.

“Clearly, horses given furosemide prior to a race or performance will become acutely dehydrated, and during a race or strenuous performance they will get hot,” he said. “So, the first thing they need following the race or performance is to get rehydrated and cooled off. Thus, they need to drink.”

He said horses should be permitted to drink as much water as they want when they come off the racetrack or complete a performance.

“The too-frequent practice of limiting water intake following a race or performance until a horse is ‘cool' is clearly contraindicated,” Potter said.

Salt Therapy

Australian Richard Butterworth has developed a way to get sodium into a horse via its respiratory system and skin by standing in a salt chamber for 15 minutes per day for three consecutive days. He presented his theory, which so far is unsupported by science, to the Horse Tech Conference in London on October 18.

Butterworth claims his Equine Salt Therapy rejuvenates cells, clears mucus, treats skin diseases, help wounds to heal, speeds up recovery from travel sickness, and reduces anxiety.

Leading Australian trainer Peter Moody was the first trainer to construct and use the salt chamber at his yard, and Australian veterinarian Christopher Elliott saw favorable results, Horse & Hound reported.

Butterworth is seeking researchers to study his Equine Salt Therapy. For now, he has only anecdotal reports of its benefits.

  • Old Timer

    What a complete and utter farce of a study to compare to Thoroughbreds!!!

    Giving an animal lasix daily?!? Heck yes, there is a possibility of having a sodium imbalance, not shocking at all! I’m surprised actually that this is the only issue they found by giving it “chronically”.

    Everything about this study is wrong: “herd of ponies”, “sedentary life”, “chronically administered” and finally, what the heck kinda stalls are these poor ponies in that they can’t accommodate Thoroughbreds?!? Are they the size of dog house or what. I’m just not able to comprehend how anyone would honestly with an oath on their mother’s life suggest that this study is in any way relate able to the racing, training, and administration of Lasix to Thoroughbreds.

    Seriously Ray, this study is worth nothing more than people that want to, I guess, run ponies and give them Lasix daily for some unknown and completely ridiculous reason.

    • i would say that study is as valid as many studies for people using rats, mice, etc.

      • Old Timer

        Exactly, how many super wonderful new things have you heard about curing this disease and the next, only to find it doesn’t actually apply in people? A lot of them! Again not apples to apples here by any stretch of the imagination.

    • HowardRoark314

      So your position is that Lasix is the first drug in the history of the world to have zero negative side effects? Boy are we one lucky industry, thank heavens for veterinarians – our horses are so fortunate to have them.

      • Old Timer

        My position is that this study is wrong on it’s face to be compared to Thoroughbreds that are actually racing.

        There is an effect that is negative, and that’s the horse losses water right before a race. I don’t think anyone has ever said that’s a good thing when taken on it’s own merits, and it’s not a side effect, it’s a direct result of Lasix being a diuretic.

        The question becomes, and here’s the tricky part, does the reduced water the horse is able to retain prove to be more important than reducing the potential of having blood in a horses lungs. To this point, the answer by many vets is “No”, it’s more important to reduce the incidences and severity of EIPH in a horse than the short term effect of having less water.

        I thank the heavens often that there are many excellent veterinarians that dedicate so much of their time to bettering our horses.

        • Billy

          You should prolly look into dehydration and what it does also potassium losses…..muscle function must be at a premium in a racehorse and considering their 90 percent muscle id say its quite a big deal

        • Meg Hiers

          No more wrong than a few vets deciding they should try to give lasix to racehorses back in the day to see if it would help with bleeding without doing too much noticeable harm without much research into the full effect of lasix in horses.

          • Always Curious

            In the really old days they withheld their water to accomplish the same thing, carry less weight.

          • Old Timer

            Honestly your comment makes no sense.

            I’m referring to the fact this this study is trying to correlate sodium imbalances to Thoroughbreds using completely different horses, administrating timings, and overall conditions is what makes this study wrong. Not doing the study.

            Completely different points of contention.

            Someone wants to go out and use a drug to stop horses from tying up post race and it has minimal to no side effects, go for it! All for study and research. What I’m not for is making board based correlations that are immediately observed to be a false in their premise.

          • Meg Hiers

            Just saying that maybe before TPTB blanket approve a drug approved for a different animal completely, maybe a few good studies of its effects should be completed so that the issues are known beforehand and can be contemplated rather than realizing later, oh it appears it might also have other issues. Considering that there is likely no drug out there completely without side effects, this was inevitable. Now every study is going to have to deal with the politics of racing attacking its conclusions.

          • Old Timer

            There have been studies going back as far as the 70’s when Lasix was first introduced, so the TPTB didn’t just blanket approve it. Lasix was studied then and found this was the best option at that time in comparison to all the other options available to treat EIPH. The funny part is that Lasix still is, AND has been substantiated in the Jockey Club’s own study via the RMTC down in South Africa. The study shows in what is TO DATE, the best study ever done in any racing jurisdiction, in the use of race horses, that Lasix does as it’s intended, i.e. it’s efficacy is correct in the use of reducing and eliminating EIPH. Period, there’s no debating this. Read the study.

            Did you know that Dihydrogen Monoxide (DHMO) is a colorless and odorless chemical compound,
            also referred to by some as Dihydrogen Oxide, Hydrogen Hydroxide,
            Hydronium Hydroxide, or simply Hydric acid.
            Its basis is the highly reactive hydroxyl radical, a species shown to mutate
            DNA, denature proteins, disrupt cell membranes, and chemically alter critical
            neurotransmitters. The atomic components of DHMO are found in a number of caustic, explosive
            and poisonous compounds such as Sulfuric Acid, Nitroglycerine and Ethyl
            Alcohol. Yet we give this to horses all the time, everyday in fact.

            OH I forgot to mention, Dihydrogen Monoxide is also called water, we need to do more study!!

            No not really, here’s the facts. Everything will have a negative side effect. Don’t care what it is. When studies like this try to make correlations that are false on their face, because well science, that doesn’t mean more study needs to be done. It means stop propping up BS studies that create a facade of science to push an agenda.

        • Always Curious

          I agree a TB study is needed to show a breed specific answer. However you miss the point that the study was about basic equine physiology. It’s results were explained in that way, and said further study is needed. Those things you just mentioned like race preps, level of activity, ways of accurately determining how much fluid is lost, etc. You have to start small w research so you can determine how to proceed. Small numbers of horses is poor science if you are making big statements about the results. I don’t think they did this here.

          • Old Timer

            This study did said that here IMO. They made in this interview wide ranging assumptions that have no correlative data. Again, nothing shocking at all about sodium imbalances.

            They want to do a study that uses horses in racing. Go for it, don’t care. Get some people to step up and participate.

    • DeniseSteffanus

      The specially constructed stalls have a collection pan underneath them so researchers can measure the amount of urine excreted. Animals are not housed in these stalls other than for study purposes.

      • Old Timer

        So the stalls have no bedding in them in order to make this work?

        • Meg Hiers

          They likely have some sort of non-absorbable chips that allow for some some soft footing but that also allows for free drainage down to the pans.

      • Always Curious

        All you would need is to know is the weight of the pad or whatever they are standing on, weigh after they pee & subtract the weight of the pad when dry. Or something like that. Lol

  • JamagotasueU

    Same problem alot of Jockeys struggle with when using sauna or sweatsuits to lose weight.
    Then they are afraid of taking saltsupplements because of the water retaining effect.
    Screws up the kidney functions for them if the heart don’t give up first.

  • Bryan Langlois

    It does amaze me that everyone seems to know how to do the right studies to look at how lasix affects horses long term…yet no one seems capable of actually doing it. I don’t know if it is a financial reason or otherwise. Since every single horse in the US basically races on it…there is not like you could not have a large enough study population that you could easily blind the researchers to. I know there are studies that exist from other countries, but to do a large scale study in the US using housed in the typical backstretch environment under regular racing conditions should be easy enough to do. Now…here is the kicker to it. The researchers would have to know exactly what other drugs (legal, illegal, or so new they are still being experimented with) were given to each of the horses so they could know if these other drugs interacted with the lasix in some way to affect the levels being tested for and tracked. Doubt anyone would be willing to sign on to have their horses as part of the study then even if they were granted immunity somehow.
    I agree the study here has many many flaws when trying to determine true effects. I do believe even the regular use of lasix long term in horses when running has to have an effect on their overall health long term. The question is who is going to be the brave and rich soul who can have the gusto and capital to really prove or disprove it in a proper study.

    • Always Curious

      You need a separate study for the effects of Lasix w other drugs. Every horse would need on just one specific drug and the other horse drug free. You would need several horses for each drug to make the results meaningful.If you want to do a drug combo, even more horses.

      Big Horse Pharma is not going to fund it IMO. Big Pharma for humans would not want their drugs associated with doping horses. Studies like these (small) are needed to get the ball rolling on research. I really like this article because it points to the need for more study. And what we know so far.

  • Always Curious

    I really liked the article Denise Steffanus. There was a lot of info. I learned. Glad it was such a detailed or comprehensive article. It covered how the research was done, not just a generalized statement that “studies show blah blah.” I never trust those kind. The media has it wrong most of the time.

  • Always Curious

    Wow, that’s a lot of info. I will Wade through it when my brain has a freshening. Thanks!

  • Racing Fan

    The most overrated medication of all time. The vets have done a great job convincing trainers why it’s necessary and the trainers have bought it hook, line and sinker.

    • Really?

      Hate to tell you but vets don’t make money on lasix. If you have an alternative to share please do. It will make you a billionaire.

  • DanM

    Increased blood volume as a result of additional salt consumption caused by Lasix induced craving is the part that justifies additional study on wider equine populations. The side effects appear to undermine the intended benefit of the drug. I hope more research will be conducted, but the pharmaceutical companies that profit from these drugs see people AND horses as nothing more than revenue generators.

    In other news, 91% of Americans age 65 and over are taking a prescription drug. That number is 69% for ages 45 to 64. Advocates who push for decreased drug use in humans and/or animals should expect to be a principled David up against a corrupt Goliath.

  • Linda Light

    Dr. Houpt advises a salt block yet a bucket of loose salt makes it easier for the horse to obtain the salt and this isn’t mentioned at all. Also, furosemide( Lasix) does a lot of things in the body. No one has ever proven that reduction of blood pressure is why it helps EIPH. Also, her concern about Lasix making EIPH worse is contradicted by the papers that show that it improves the condition or causes no effect at all.
    Perhaps it helps EIPH because it dilates veins in the lungs which helps blood flow continuity. The pathology findings in EIPH of decreased vein diameter along with perivenous fibrosis suggest that EIPH may be caused by constricted veins being unable to drain the increased arterial inflow to capillary beds.m What goes in must go out. If the veins don’t have the flow capacity then logic would say the blood will ooze out of the capillaries. In times of intense exersize much more blood flows through arteries into pulmonary capillary beds. if the blood can’t get out through veins, it will get out the only other way, through the parenchyma of the lungs. Just because Lasix is a diuretic doesn’t mean that’s why it works for EIPH.
    Also, there is the possibility that Lasix actually benefits horses rather than is bad for horses altogether. It seems like the positives outweigh the negatives despite attempts to prove otherwise so far.
    Dr. Linda Light

    • Really?

      Thanks Dr. Light. I’m tired of people thinking trainers are evil for using lasix. I’m sure it’s overused but we just don’t want our horses to bleed. We need more research so we can protect our horses. I’m sure it’s not pleasant for the horse. We need alternatives and tips for counteracting what may be side effects of lasix like dehydration or “thumping”. You are right, at this moment the positives outweigh the negatives in most cases.

  • John G. Veitch

    Giving Lasix daily seems to me a way to skew the data, not to mention on sedentary “ponies”. So there’s some variables in the study. I’m also taken back by Potter’s statement. “So, the first thing they need following the race or performance is to get rehydrated and cooled off. Thus, they need to drink.” That’s been standard procedure post race for a Thoroughbred since racing started.

  • Dave Stevenson

    would be interesting to move the study to a training centre and restrict to 2 y.o.on lasix. Test for blood chemistry changes that would abnormally effect general growth patterns and specifically bone, ligament and lung development.

  • Dadnatron

    This was a ridiculous, click bait study, which has no more validity than giving them chocolate. The ‘treatment’ was in no way similar to how it is administered in TBs.

    The study would have more validity had she simply administered it once a week, which would more closely represent the way it is given (administered before a race and before hard works) But then… it would have shown nothing, and therefore, she wouldn’t have been able to get 1. The funding… and 2. The obvious outcome of chronic use of a diuretic.

    I agree with Bryan… doing the research correctly isn’t what is causing the problem… there is simply no one without an agenda. Finding a dozen OTTB would NOT be difficult or expensive. You could probably get them free and clear if you simply put out the word. I understand she couldn’t use them because of size, however, her choice in how often she administered it as well as how she replaced the sodium and other electrolytes is so far and away outside of reality, that the entire study is laughable.

    It is nothing more than click-bait. It is RAMPANT in medicine… so I am not surprised it is apparent in the Vet world as well.

  • Judy Gaddis

    Research be damned. Detaining these ponies in those collection stalls is the same equivalent causing the uproar of the treatment of PMU mares! And no, I have NOTHING to do with that PETA organization that is the biggest farce on the planet!

    Lasix is a drug that (as another poster said) trainers have convinced owners their horses “need”.

    How about we ban it’s use period. That would end the questions of it’s use as well as the unnecessary tests being done with no regard for the animals involved in the testing. If a horse needs a drug, ANY substance, in order to win races then perhaps that horse shouldn’t be on the track in the first place!

  • McGov

    Salt is something that should be added to every athletes food intake and even more in the summer. With racehorses, you must add quite a bit of salt to every meal, regardless of Lasix usage.
    We are electrical machines that require continuous conductivity and this is easily reduced through sweating. Check out salt content within recommended athletic drinks etc and you might be surprised.

    • Fred and Joan Booth

      We regularly have our sodium levels checked since were vegetarians and at times perform some heavy farm work during hot weather. Our sodium level is always checked every time we have a comprehensive blood analysis done.Heart disease / high HDL is hereditary in our family. We have tried all the statin drugs and they ALL caused severe muscle weakness even at the lowest possible prescribed amounts.So we now control by diet / exercise alone which isn`t too difficult when living on a farm with lots of work!

      • Tinky

        You might consider trying the natural ‘father’ of the synthetic statins – red yeast rice. It’s very effective, and there is probably a good chance that the side effects would be minimal.

        Beware of propaganda from mainstream medical sources, though, as RYR is a threat to a huge revenue stream.

        • Fred and Joan Booth

          Thanks for the info! Where or what store might carry it? We have Kroger stores in our area as well as Costco and Safeway a few miles away. We want to beat our George Sr.s record of not having heart problems. He sadly did not make it to his 70th birthday he was a couple of weeks shy when ha passed. He had a heart attack at 63 and remarkably he recovered very well from the double bypass surgery. But the blasted buildup of plague in his arteries caused him to have several strokes which eventually with help from Joan, his wife, he recovered from. Sadly he no longer could operate his construction business and the two sons were not good enough with algebra or mathematics to continue.

          • Tinky

            You’re welcome! It will probably be necessary to source it at a ‘health food’ type store. Whole Foods used to carry it, but it’s been years since I last checked.

            Alternatively, you could order in online from many sources.

            I had a terrific doctor in South Florida who was quite open to effective and safe alternative medicines. He recommended RYR many years ago when I showed elevated HDL, and it worked well and quickly. No side effects at all, in my case. There is plenty of info online, of course.

            The main argument against its use is that the ingredient that is also present in man-made statins, monacolin K, appears in varying amounts in the natural version. So, I would suggest some research to see if there are particular brands that have reliable doses.

            Also, to be clear, it is possible that you will experience the same type of muscle-related side effects. My view, however, is that there is a good chance that they will be less pronounced with RYR, as there are no added, synthetic ingredients that could compound the side-effects.

        • Michael Castellano

          I take it, with zero side effects. And it lowered cholesterol and tryglicerides.

      • McGov

        I was very conservative with salt and horses until one day an equine nutritionist took the time to explain how important salt is for a horse and how my couple tablespoons in every feed, was not going to cut it.
        I followed his advice and noticed a remarkable improvement in hydration. I was very surprised how much salt a working horse should have in a day.
        Some horses are fussy about these things and you have trick them a bit into eating….things such as jello powders or whatever flavours the horse prefers that can mask the salt etc…mixed in with feed etc.

  • David Juffet

    Could someone tell me why on any given race day 99% of the horses entered are on Lasix? I wonder why the integrity of our sport is 99% compromised.

  • G. Rarick

    You might want to fix the lead to make it clear that few racehorses IN THE UNITED STATES compete without lasix. Somehow, the rest of the world gets by without it.

  • Dr. G

    Getting rid of Lasix would mean destruction of the American Thoroughbred breeding industry. I’m convinced that EIPH is in part genetic. American breeding stock is carrying the predisposition or sensitivity for EIPH. If Lasix was banned, most of our breeding stock would be useless. It would take years to rebuild. The European stock would take over in the meantime.

  • Steve M

    Key missing info regarding who funded the study? The Jockey Club??

    Apparently overdosing ponies with drugs causes side effects. No way.

    Maybe they should read the double blinded gold standard study prepared by Dr. Hinchliffe regarding the proven efficacy of furosemide in racehorses.

    Their next study may show that an increase use of reefer causes overconsumption of pizza in sedintary scientists.

    This smells like the latest The Jockey Club dredging of a second rate study (performed in 2016) to further their agenda.

  • Michael Castellano

    I have no studies to cite, but one can use common sense. Any drug that causes dehydration certainly seems capable of washing other important nutrients and electrolytes out of the body. Exactly how and what those elements are is something that should be investigated in controlled studies, but one thing I like to remind anyone taking a drug like this is that the so-called “side effects” are really effects in many situations. And these drugs will vary in their effects from individual to individual. I find the argument that Lasix benefits more than it hurts a horse extremely short sighted and problematic, and guarantees that horses with the trait of bleeding excessively after a race get those traits passed along when they are bred. Making Lasix virtually universal was a decision born of expediency and economic self interest which may be having draconian long term effects on the breed, and also opens up the door for the introduction of other substances to boost short term form.

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