Better Questions to Answer - by Eric Mitchell

No debate regarding the use of the anti-bleeding drug furosemide (known as Salix or formerly Lasix) is complete without a call for more research.

The Jockey Club pushed on this front during a recent meeting of the Kentucky Equine Drug Research Council, where it lobbied for a study to look at the effectiveness of Salix given at different time intervals prior to a race (see The Wire, page 17). The KEDRC advises the Kentucky Horse Racing Commission on medication policies and awards money for funding of medication studies.

Salix is highly controversial because it is the only race-day medication allowed in North America. Horses are permitted to get Salix at least four hours prior to a race as a preventative for exercise-induced pulmonary hemorrhage, also known as bleeding. The drug is a diuretic, meaning it causes horses to urinate a lot and consequently drop significant amounts of body weight from the water loss. Studies have show this weight loss contributes to enhanced performance, which is why the medication is so controversial.

On the one hand, the medication is considered important in racehorse welfare because research has shown it reduces incidences of EIPH. On the other hand, its use does influence performance and its long-term effects on racehorse health are unknown. Anecdotally, trainers have said horses given a regular regimen of Salix take longer to recover following races.

TJC’s proposal recommended studying the effectiveness of Salix 24 hours, 12 hours, six hours, or maybe even two hours out from a race. A formal proposal to this admittedly narrowly focused study has yet to been drafted.

KEDRC members Andy Roberts, a veterinarian representing the Kentucky Harness Horsemen’s Association, and Rick Hiles, president of the Kentucky  Horsemen’s Benevolent & Protective Association, both don’t like the proposed study because TJC has already made it clear it wants U.S. medication rules on par with the rest of the racing world, which bans all race-day medication use. Roberts called the proposal “a ridiculously thinly veiled attempt to get rid of Lasix.”

Well, it would certainly be one way to address the race-day issue if a study showed that Salix could be given more than 24 hours out but let’s hope the current research push doesn’t stop there. A real issue with Salix is whether racehorses should routinely be given Salix at all. Two recent studies indicate maybe it should not.

A presentation given during the recent International Conference on Equine Exercise Physiology, held June 16-20 in the United Kingdom, showed evidence that a single dose of Salix caused a negative calcium balance in horses for 72 hours after it was administered. The study was done by Kentucky Equine Research, based in Versailles, Ky. Co-author and KER president Dr. Joe Pagan said his research, done on six Thoroughbreds, signals the need to do a more robust study on the effects of Salix on mineral balance and soundness in racehorses.

Then, an Australian study published June 11 in The Veterinary Journal indicates a genetic component to epistaxis, which is the most severe degree of EIPH where blood is observed in the nostrils and does negatively affect performance. Race records and reported occurrences of epistaxis in 117,088 racehorses entered in races or official barrier trials between Aug. 1, 2000, and Feb. 22, 2011, were analyzed by the team of Brandon Velie, Herman W. Raadsma, Claire M. Wade, P.K. Knight, and Natasha A. Hamilton. The researchers looked at both genetic and non-genetic factors that contribute to epistaxis.

“While this is only the second published study to estimate the heritability of epistaxis, it is worth noting that these estimates, along with those by Weideman et al. (2004), provide strong evidence to suggest an equal or greater genetic contribution to epistaxis compared to many racing performance traits,” the study states.

“It is possible that epistaxis requires specific (combinations of alleles at adjacent locations on a chromosome) that may increase the vulnerability of a horse to pulmonary capillary stress failure during exercise. This genetic susceptibility would then most likely result in some horses being more sensitive to certain environmental triggers, potentially explaining the variation in significant non-genetic factors between populations,” the study continued.

The authors raise the question about medication masking such a genetic trait but don’t go so far as to suggest horses genetically predisposed to epistaxis should not be breeding animals. They do note that such knowledge would be valuable to owners and trainers to “allow for modified management plan” to reduce incidences of epistaxis.

It’s understood small steps are required to gather good data. But the resources for quality research are precious, so let’s be sure to  also push for studies that lead to substantive change


Leave a Comment:

Old Old Cat

You are a voice crying in the wilderness.  No one hears you.  What you are saying is "We need an independent non-political group to sponsor an unbiased scientific study of the short-term and long-term effects of Lasix on the performance and well-being of the Thoroughbred racehorse."

Who's going to sponsor it?  Who's going to believe it when the results are published?  Who's going to follow the recommendations????

24 Jun 2014 3:56 PM

studies on lasix have already been done.

Lasix both prevents EIPH and allows the EIPH horse to race on dirt tracks without serious bleeding.  The notion to EIPH is genetic is ridiculous and done by a biased researcher.  Why are they doing lasix studies in England and Australia.  Conduct one here in the USA on a dirt track in Louisiana in the summer time.  Force a rep of the hay, oats and water alliance stand there and watch while the non-lasix horses get to bleed from the lungs in that humidity.

24 Jun 2014 5:45 PM

For openers, why not do a thorough re-read (assuming that you and some others read it, to begin with) of the Hinchcliffe, et al study before jumping to any (other) conclusions. That study was the most comprehensive, and offered fairly certain conclusions. For those who choose to deny its results, why not attempt to duplicate, or enlarge its methodology, instead of wasting time and money on attempting to find "fringe" answers. I think the reasons are obvious; the agenda is to abolish Lasix for use in the racehorse and the best way to accomplish this is by avoiding studying the real issues and instead throwing some irrelevant data out there in hope that the less informed/and those with preconceived agendas will accept or readily swallow. Not unlike what you're trying to accomplish by this piece--which when read by some would appear open-minded, but its content tells a different story. You are not educating your readers here, rather you are maintaining their ignorance. The Jockey Club's proposed study is a joke, and the other studies you cite offer little to nothing re-the fundamental questions. When you're on the wrong side, the best way to win the day is to throw into the mix a lot of junk and hope that something sticks.  

24 Jun 2014 7:05 PM

I forgot to add that you said it all in your title "Better Questions to Answer..." Why are these "questions" BETTER? You're labeling them as "better" and by doing so you are telegraphing your agenda...I'd be curious to read your counter.

24 Jun 2014 7:09 PM
Seabiscrateriat O' War

Lasix needs to be banned for all horses except confirmed bleeders. Horses can run without it, look at what Alysheba did in the Meadowlands Cup when he was taken off of Lasix.

24 Jun 2014 10:15 PM


Lasix should be studied. It is wildly over used in this country. If our horses ran on feathers and had a speed limit of 25 mph the trainers and vets would still be pumping them full of it.

We didn't use it for a couple of years on the 2 year olds on breeders cup day and nothing happened. The problem is the trainers want it, the vets make there money giving it and the owners want it. The dirt track only in America makes me laugh. I went and looked at grass races run in this country and 98 percent of them were taking Lasix. Is our grass funny too or are we all smoking too much weed. The extreme weight loss with low electrolytes might account for some of the break downs in races.

I'm a big race fan and want our sport to prosper, get rid of all drugs like the rest of the world on race day. How can it be good for a dehydrated animal to run his guts out. When you think about what we are doing it doesn't even make any sense. Its not about the dirt, that's the only excuse people can come up with. Then they pump there grass horses full of it too!!!

24 Jun 2014 11:53 PM

In response to Old Old Cat I would point out that independent non political unbiased research is conducted by other sports leagues and organization with regards to health and safety issues and they enact policy based on the findings. The issue here really goes far beyond any single medication and is going to have an impact on many aspects of horse racing so it's imperative that as much information be obtained so wise decisions can be made to better the industry as a whole.

25 Jun 2014 4:21 AM
Thoroughbreds are the best

There certainly appears to be a genetic component as well as a training component to EIPH.  Lasix in thoroughbreds is a relatively recent addition. In the past, bleeders were banished from the track. We ended up with a very nice Hyperion granddaughter in our hunter barn 40 years ago because she had bled. How many thoroughbreds actually will suffer from EIPH?  If the percentage is small (less than 10% ??) Then why are nearly all of the North American horses run with it? If it is a large percentage, what has changed that has increased that percentage so drastically? Clearly this has to raise questions. If they all need it now, why didn't they need it in the past?  Has the gene pool changed? Have the track conditions changed? Or is it easier to get a horse ready to race? Sorry, but hay, oats and water are how a horse should be raced. If they need something more, perhaps the question isn't what to give them to keep them in the game, but should they be in the game at all at this time?  The widespread use of any drug should raise all kinds of questions in everyone's minds.

25 Jun 2014 8:26 AM

We, those of us that breed and train, have known for years that bleeding is hereditary and a true bleeder will bleed through lasix, salix or whatever else they decide to call it.  When a mare bleeds, her foals bleed and their foals bleed, what else do you call it?

25 Jun 2014 8:35 AM


You want the sport to prosper? A good start might be for you to educate yourself about this issue. Not a single statement you offered is valid. What a few examples: 1. The no-Lasix Breeders' Cup 2 yr. old races proved nothing; and there were bleeders. EIPH has a cumulative effect--read about it!. 2. Lasix causes no EXTREME weight loss, and the electrolyte loss is quite temporary. 3. Rather then Lasix causing more breakdowns, it has been conclusively shown that Lasix prevents many breakdowns.--NYRA study pre vs post permissible Lasix. 4. EIPH occurs in BOTH  turf and dirt races. Somewhat less so in turf races due to less relative impact...Thoroughbred racehorses bleed-the majority bleed to one degree or another. They bleed without Lasix now, and they bled without Lasix back then. The difference is that back then there were no fiber optic laryngeal/bronchoscope to observe the non-epistaxic bleeding. Understanding this doesn't require a rocket-scientist mentality--merely an open mind with some motivation to read. EIPH causing harm to the horse; degree of harm varies. An initial small bleed increases the risk of greater bleeds in the future. So preventing the use of Lasix in 2 yr. olds is a particularly cruel and uninformed policy...Yes, by all means study it more, but make them meaningful, well thought out studies.    

25 Jun 2014 1:17 PM
Byron Rogers


It's pretty hard for a paper that undergoes peer review by 3 independent scientists to survive any "bias" you might like to believe exists. The study was done on over 100,000 horses, by far the biggest population looked at for EIPH and they found a genetic component to it. That is, certain sire/sirelines and certain female families have a predisposition to bleeding. There was a leading sire called Barlett's Childers (1716) who was a full brother to the brilliant Flying Childers but he was also known as "Bleeding Childers" because he was a bleeder and never raced. He was a leading sire of England and is the great grandsire of Eclipse who is everywhere in modern pedigrees.

In one of the studies that they did in South Africa they flat out named leading sire Al Mufti as a source of bleeding in South Africa. He's out of Lassie Dear whose daughter Weekend Surprise produced Summer Squall a noted bleeder himself. It has a familial component. The authors also mention that there is an environmental component to it that may be genetically linked. Have you ever wondered why not all horse bleed in humidity?

Sceptre, I think that was Eric's point. There are other studies that need to be done other than the one proposed by the Jockey Club. Pagan's study is the most alarming. If a single dose of Lasix is causing mineral loss, what is repeated use doing. A larger study on that would be of greater benefit to horsemen also as it would provide guidelines to proper supplementation if Lasix use continues.

You rightly point out it is a progressive disease/issue but did you read the paper published last month by Hincliff that showed that only horses that bled through the nose (Grade 4) had compromised race careers?

25 Jun 2014 3:30 PM


Glad you've been following this blog. Now, to your points:

I think it rather likely that there's a genetic link to EIPH. The study you mention, however, seems to find evidence only for the epistaxis genetic link. I haven't read that study, but would guess its true consequence is very much in the details. More importantly, it appears not to address all other degrees of EIPH. Now you then make mention of a very recent Hinchcliffe study to which I'm not privy (and after reading your post, I tried in vein to locate). Would appreciate your help in locating it. Your conclusion from it suggests that only level 4s manifest compromised performance (I know, this isn't precisely what you had stated were his findings, but if what I said doesn't follow, then there can be no validity to what you state was his finding). So, do you really believe that a level 3 EIPH has no effect on performance? ..You also mention that S. African genetic study (Al Mufti sire as one of their examples)-not the original Hinchcliffe study). Well, I read long ago that study, and found it to be very flawed and useless. Suggest you read it again with an unbiased mind. As far as I'm concerned, the only potential new news here is that very recent Hinchcliffe study. Dr. Pagan's findings from that very small group is hardly the stuff of a well controlled sufficient population study. And, what's so alarming about a negative calcium balance for 72 hrs.? Implied in this is that the calcium level returned to normal by hour 73. And, how negative was that balance, and did he perform similar tests on controls? So far, much of what I see is just smoke. The original Hinchcliffe study was pretty darn persuasive, and I haven't forgotten the NYRA stats for pre and post Lasix administration. What about that one; or is it simply conveniently forgotten?

I'm about helping these horses' lives; I don't give a d..n about performance enhancement, nor do I care if the industry prospers or dies. My agenda is but one-can you, or the other non-Lasix proponents say the same?  

25 Jun 2014 6:08 PM


I'm still searching and have yet to find any citation re-any 2013 or 2014 EIPH study by Hinchcliffe.

Re-your worry about furosemide (Lasix/Salix) causing hypocalcaemia in horses-try to find one reliable study that documents this. Recall that I am a physician, that Lasix was a commonly prescribed drug, certainly in my practice back then. Hypocalcemia was not an issue with Lasix, and was prescribed to many elderly females, for example. If you study the complicated pathway (human) of lasix' effect you'll notice that the Calcium ions are reabsorbed lower down in the process. Ok, humans aren't horses, but show me the evidence that their physiology differs in this regard. Yes, Lasix does have the capacity to deplete some electrolytes, but Calcium isn't the one normally of concern. Perhaps, so much for this Lasix---depleted calcium---brittle bones angle. Another red herring?...I'm far from an authority on this, but let's not be so welcoming of very potentially false assertions-merely because they suit our agendas. And, what's the real agenda for many?-- they want to appease the "rest of the world"-even if the rest of the world is misguided. So, the hell with the horse; commerce is king, and this commerce has many facets, among which is promoting the side taken by valued clients. For example, Mrs. "Barbaro" talks (and writes) and everyone intently listens. Never mind that there is little to no substance in anything she offers on this subject. Science will eventually give us the answer-if science is given a FAIR opportunity to find it. Until that day, the present evidence should rule-and that present evidence tells us that Lasix aids in the minimization of EIPH. I'm not interested in the anecdotes from the non-scientific community-and neither should any of you.    

26 Jun 2014 12:01 AM
Brown brother

I breed and own thoroughbreds and remember the days when LASIX was forbidden.  I wish all my horses trained and ran drug-free.  But, I am not an expert and hire and trust my trainers to do what's best for my horses first and get their peak performance on the racetrack second. All of my trainers, from the old school horsemen to the new hotshots and everyone in-between runs my horses on LASIX, as do all the highest achieving trainers in the sport (Mott, Baffert, etc.). Although I feel I do my due diligence as an owner to find out what's best for my horses, which I love and care for until death from old age or responsible transfer to lifetime homes and post-racing careers, since I am not with the horses day-to-day I don't feel comfortable giving orders about decisions on any medications.  Perhaps I am copping out, but my point is that even owners who love their horses and strive to be responsible end up running and training on LASIX and other medications beyond hay, oats and water.  

26 Jun 2014 5:08 AM
Byron Rogers


Here are the two recent studies I referenced.

27 Jun 2014 3:36 PM
Janis from Winnipeg

The study that found that there was a calcium deficit as long as 72 hours after Lasix use was interesting, particularly in light of anecdotal trainer comments that it takes horses longer to get back to races when using Lasix.  I have read elsewhere that the horse has not actually even started repairing the calcium deficit 72 hours post-Lasix so you are probably looking at an additional two or three days for that to occur.  Calcium is a crucial element in muscle contraction.  It seems obvious that a horse that was suffering a calcium deficit would not appear to be training well and this may well be part of the reason it takes them longer to get back to races when on the Lasix program.  When you consider that many trainers also give Lasix for fast works while training, it probably compounds the problem.

We do need more study on a number of aspects of Lasix use, and the above is one of them.  How long is there an actual deficit, and what effect if any does it have on muscle contraction and training?

I've read over and over again that people are concerned that horses can't seem to race as much as they used to.  This could well be a major factor in that.

29 Jun 2014 3:50 PM

janis from Winnepeg:

Good post. Yes, by all means, we should continue to study EIPH, and the pros and cons of Lasix administration. You're concerned about the potential for calcium depletion and issues re muscle contractility with Lasix, and if so to what degree and duration. Well, your observation about Lasix use in breezes may just address (and potentially put to rest) some of your concerns. Yes, trainers often administer Lasix prior to a breeze-and rightly so. For some horses this is done on a regular basis. But, those horses breeze just as regularly/frequently as others who don't receive it. If Lasix did have such a calcium depleting effect that manifested in issues re muscle contraction then those horses who train/breeze on it should have interrupted training cycles-which they don't.  

30 Jun 2014 11:40 AM
Janis from Winnipeg


Perhaps you could provide the data you're basing that comment on.  I don't believe there has been a peer-reviewed study in this regard, which is one of the reasons I am saying that it needs to be looked at.

02 Jul 2014 9:07 AM

janis from winnepeg:

No, I'm not privy to any "peer reviewed studies" re-racehorses receiving Lasix in workouts/muscle contractility issues. Rather, my remarks are based on my experience with horses that have been administered the drug prior to breezes and having never noted the issues you hypothesize. Also, let's face it, racehorses are routinely given serum/blood tests and calcium levels are among the parameters tested. If anything, lower potassium and chlorine would be more a concern with Lasix. OK, we can study all this more, but in the end my strong guess is that we'll find that Lasix had nothing to do with today's (and yesterday's) lower number of starts. Where the $ and efforts should really be directed is in greater oversight and technology to minimize severe injuries. This Lasix issue is a red herring-we're overlooking the really big problems.  

02 Jul 2014 7:10 PM

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