Breed Integrity - By Eric Mitchell

 (Originally published in the June 25, 2011 issue of The Blood-Horse magazine. Feel free to share your own thoughts and opinions at the bottom of the column.

By Eric Mitchell - @EJMitchellKy on Twitter

By Eric MitchellA 2004 South African study that identified a genetic link to exercise-induced pulmonary hemorrhaging (EIPH) was one of the most sobering bits of information disseminated at the International Summit on Race Day Medication, EIPH and the Racehorse held at Belmont Park June 13-14.

The results of the study were shared by Dr. John McVeigh, a principal with the Baker McVeigh & Clements racetrack practice, which has clinics in South Africa, England, and France.

“The conclusions were very strong,” McVeigh said about the study done by Hans Weideman, S.J. Schoeman, and G.F. Jordaan, that showed EIPH is highly heritable, particularly through stallions.

How the South African study relates to the use of Salix in the United States is that more American stallions are being exported to South Africa and the average number of bleeders per runners is increasing in that country, according to McVeigh. The use of Salix as a preventative medication in the United States in at least 90% of runners hinders reliable tracking of horses that actually have significant cases of EIPH. Race-day use of Salix is banned in South Africa, and all bleeding cases are carefully monitored. For example, all horses are walked around a paddock ring for five minutes following a race so veterinarians can inspect for any signs of bleeding.

Dr. Scott Palmer, past chairman of the American Association of Equine Practitioners and current chairman of the association’s racing committee, said this study was one of the surprises to come out of the summit. He said he had not seen the study and intended to have it reviewed by an epidemiologist to determine if the methodology holds up.

“It is certainly a provocative study,” Palmer said. “I am not aware of any other studies that show a genetic link. There will certainly need to be some additional studies done to collaborate the results.”

If the results are verified, then the American breeding industry has some difficult decisions to make.

Even if Salix is no longer allowed on race day in the U.S., what is the breeding industry’s responsibility in identifying stallions with EIPH? In Germany, which has a no-nonsense policy when it comes to breeding stock, a stallion that has raced on medication is allowed to produce registered foals, but those offspring are ineligible to earn breeders’ premiums that account for 24% of Germany’s purses for 2-year-olds and 3-year-olds and 20% for older horses.

According to an article that appeared in The Blood-Horse of June 4, 2011 (page 1522), the disincentive to breeders is pronounced. Racing on medication eliminates a stallion’s commercial appeal.

Should a similar program be considered in the U.S. if it is confirmed that EIPH has a strong genetic component? What do we do with male horses that have shown to be bleeders on the racetrack, and should this information be readily available to breeders? Is cleaning out a genetic trait already associated with poor performance on the racetrack a responsibility of American breeders and the stud book?

These are tough questions. First, what constitutes a serious bleeder and at what point does the condition truly affect racing performance? Right now the evaluations are totally subjective. Even during the recent medication summit, there were widely differing definitions of a “bleeder” among countries.

The horse genome, however, is now mapped out. It is only a matter of time before the genes responsible for EIPH are identified. Once that happens, then the decision is no longer subjective.

The American Quarter Horse Association dealt with a genetic condition called hyperkalemic periodic paralysis (HYPP), uncontrollable muscle twitching and substantial muscle weakness or paralysis among affected horses. It is caused by an autosomal dominant gene linked to the stallion Impressive, a prolific halter horse. The AQHA requires genetic testing for the genetic trait and has barred registration of horses that possess the homozygous form of the gene since 2007. Heterozygous horses are still eligible for registration.

It will likely be years before a firm rule either further restricting race-day Salix or banning it outright is implemented. In the meantime, the globalization of racing will continue. Considering many trainers and breeders overseas already view American bloodlines as suspect and “tainted,” now is the time to begin debating how we will ensure the integrity of our bloodlines when medication no longer allows us to hide our flaws.


Leave a Comment:

Dawn in MN

I can't believe that nobody commented on this article.  This is a very important issue.  As stewards of the Thoroughbred all parties must grab this opportunity to improve the breed.  Anyone worth their salt will stop breeding, buying and racing the horses that are passing this trait to their offspring.

21 Jun 2011 6:48 PM
Rachel NH

Ahh, the dilemma of all the right thing for the breed or the pocketbook...

21 Jun 2011 7:05 PM


I do not believe much action would be needed to rid racing of raceday Lasix. Once it is confirmed that bleeding is hereditary, capitalism will operate to eradicate it.

I can see breeders advertising that their imported stallions never raced on Lasix, do not produce bleeders and that their stud fees are competitive. I can also see buyers demanding evidence that the yearlings they are buying were not produced by bleeders. Capitalism is  a cruel master.

What I find disturbing is that it has taken 7 years for the South African study to get wide circulation.

21 Jun 2011 7:14 PM

I became a racing fan when my father took me to the track at 10 and I'm a biologist, but not a vet. I don't own a horse and I have no stake in the status quo.

From where I stand the choice is clear: the status quo is profitable in the short term but, if you love the Thoroughbred,  race day medication should be banned ASAP. Bleeders should be tracked and the information made public. Good for the German disincentive to breed more bleeders. If genetic information ever becomes available testing should be required and the result should have the appropriate consequences for registering the horse.

But I doubt that will happen. The We Need Meds Campaign is going strong and the Denial & Delay Campaign  has begun. It's odious but the best chance for the Thoroughbred is (hold your nose) passage of the bill requiring an end to race day medication.

I looked up HYPP and it seems to be spreading since the American Quarter horse is a popular cross. Not registering homozygous horses does little to eliminate the genetic defect because a heterozygous horse of either sex will pass the defect to HALF it's offspring. Heterozygous horses all have HYPP but it tends to be milder. The disease is being "managed" and it is spreading. Does that remind you of the bleeding situation?

21 Jun 2011 8:40 PM

Mr. Mitchell,

After having finished reading your report of Dr. Palmer's comments regarding the South African study (heritability of EIPH) I was left with these thoughts:

Dr. Palmer is current chairman of the AAEP's racing committee. He said that the study was one of the surprises to come out of the summit. You quote him as stating that the study was certainly provocative, and that there is need for additional studies to collaborate the results. But, despite feeling as he did, this AAEP racing committee chairman readily admitted that he hadn't even read the study. The RESULTS of this study were indeed provocative, and have already been widely publicized. Dr. Palmer is, no doubt, aware of the potential consequences from the "sound bite" conclusions of the study. How difficult would it have been for him to have located and read the study? I, for one, located it easily, read it, and was left with clear reservations about the study's failure to address (or even mention) what I felt to be fundamental variables. I am now attempting to communicate with one of the study's authors. At the moment my concern is that there will be a rush to judgement in matters related to lasix, instead of allowing sufficient time for thorough review and additional studies, including those that focus on the issue of EIPH heritability.          

22 Jun 2011 12:49 AM
Walt Gekko

This is just more fuel to the fire concerning a phase-out of Salix (Lasix) that I think is necessary for the long-term health of the sport. We raced for many years without Lasix in the US, and those horses raced far more often than those of today. Back in the day I was as much pro-lasix as anyone, but having seen what has happened, a five-year phaseout (previously noted) is necessary for the sport's long-term health.

Many points have been made, and a lot of them good ones, but the fact is, in the days before Lasix, horses ran far more often than they do today. While some of that has to do with the way horses are bred, especially for precociousness, I do think Lasix is a big part of the problem and needs to be phased out over the next five years, even if it's just to appease public perception.

That said, what may actually be more important long-term is something soon-to-be new Meadowlands owner Jeff Gural is planning starting with major stakes events for the foals of 2012 at The Meadowlands, Vernon Downs and Tioga Downs: Any horse conceived by a then-four year old stallion would be ineligible to race in such stakes events, including The Meadowlands Pace, arguably the most important race in all of Harness Racing for pacers (this originally appeared in the June 10 issue of Harness Racing Update, a PDF File at: This should force top horses in Harness Racing to race through at least their four year season starting as early as 2012.

Thoroughbred Racing needs to follow suit, and if anything expand on Mr. Gural's plan to include five year old seasons. Even if Churchill Downs is the only track to implement such a policy (horses conceived by then-four or five year old stallions not being eligible to major stakes events, including the Kentucky Derby), it would force major changes in how horses are bred, eliminating the rush to get horses running sub-:10 eighths as yearlings for instance since horses would now have to be bred for durability and endurance since they would be required to race through at least their five year old seasons. That, coupled with a ban on lasix I think would strengthen the breed long term and keep the sport's stars running longer, which probably is in the best interests of the sport long-term.

22 Jun 2011 4:34 AM

Is the stallion, Impressive, that you refer to the Thoroughbred owned by Ogden Phipps who was a pacesetter much of the time for his stablemate, Buckpasser in 1966?  Impressive was best as a sprinter, an upon his retirement, I heard he was popular as a QH sire.

22 Jun 2011 9:57 AM

I read this study several years ago when researching EIPH as the result of eventing catastrophes.  It surprised me considerably that it was not more widely known in racing circles.

If tracks would make getting Lasix permission harder, then its use would diminish, even under present rules.  But they won't, since the trainers will yell because we all know it's a performance enhancement.  

Any further studies that are done should not focus completely on stallions.  Even though the male can spread his genes much more quickly than females, females also travel widely in the TB industry.  Since we don't know if or how EIPH is linked in the gene system and what turns it on, science needs to be sex neutral until something else shows that EIPH might be sex linked to the male.

There are accounts from many years ago of great TBs who bled, so the problem is not just the US or recent. It's always been present in the TB.   Historical research would be valuable to add to population studies.

In short, EIPH is clearly a problem that needs more research.  Bringing the United States racing industry more in line with the rest of the world would be a good thing for more than just this single issue.  The FEI has been dealing with drugs for more than a decade, and they have developed a policy that the TB racing industry could emulate--although I do admit that the scale differences are daunting.

22 Jun 2011 1:26 PM

Texohky, the AQHA Impressive has nothing whatsoever to do with any Phipps TB.

It's also my recollection that the AQHA has plans to eliminate registration of N/H testing horses some time in the next decade.  

22 Jun 2011 1:30 PM

anybody bother to read the "study". it is completely bogus.  horses never bled before lasix, right?  what about the mares.  why not just import German stock. then lasix would be unnecessary. more myth making that requires careful analysis.

22 Jun 2011 4:19 PM

In the good ol' days, horses didn't run on Lasix. Before doctors used Lasix on humans for the first time, and eons before vets did the same with horses, tracks nationwide banned bleeders. If a horse bled, it didn't run, and it sure as hell didn't breed. If a stallion or mare produced a significant number of bleeders, their own breeding careers were numbered, regardless of how pretty their pedigrees were.

Look at a photo of Man o' War as a juvenile in 1919, then look at a photo of say, Uncle Mo in 2010. Look at the differences between them, and they are tremendous. Man o' War had better bone and substance than Uncle Mo, whose genes have been tainted by Lasix for five generations now. I'll hazard a guess that if Louis Feustel were to look at Uncle Mo, he would mistake the colt for a filly, because even as a three-year-old, he looks nothing like a colt from the early 20th century.

As for selective breeding, haven't we done that enough? 90% of stallions at stud in the US, Canada, Britain, Ireland, and France are male-line descendants of Northern Dancer. I know his line begets good runners with lots of flash. Of course, that much is obvious, given his quick start at stud. However, the horse himself was unsound. This could be for any number of reasons, but Native Dancer, notorious for being unsound, was his grandsire, and by concentrating both of them with all this line-breeding and inbreeding, we're concentrating infirmities of all kinds. For the last 50 years, we've been creating an infirm animal. For all we know, Lasix could've exacerbated the issue. Maybe Northern Dancer and Native Dancer should take a backseat to lines known for soundness and stamina, and only be used to add some spice here and there.

22 Jun 2011 4:39 PM


The QH Impressive is not the same as the TB son of Court Martial:

22 Jun 2011 5:31 PM

Texohky: The QH stallion Impressive was not the same horse as the one owned by Ogden Phipps. Impressive (QH) was born in 1969. He was sired by the Thoroughbred Lucky Bars and was out of the quarter horse mare Glamour Bars. He had exceptionally "beefy" conformation, which was so superlative that it made him a stand-out halter horse and a popular sire of halter horses. Do a Google Image Search for Impressive if you want to get a look at him.

HYPP is a black mark on the Quarter horse breed (as well as Paints, Appaloosas and other breeds which outcross to QH) and I've never been satisfied with the stock breed associations' failure to step up and say "no more" to registration of horses with the disease. It's a case of the pocketbook being more important than the individual horse or the overall health of the breed. I think it'd be a crying shame to see the same thing happen with Thoroughbreds.

22 Jun 2011 6:52 PM

@ Texohky,

No, this article refers to the QH stallion Impressive:

22 Jun 2011 6:54 PM

Impressive was foaled in 1969 and was a quarter horse not a thoroughbred though his sire was thoroughbred. Not the same horse as the one owned by Ogden Phipps.

22 Jun 2011 7:35 PM


23 Jun 2011 3:18 AM

In my earlier post I said I found it disturbing that it had taken 7 years for the South African study to gain wide circulation. However, I did not do my part to help others locate the study.

Here is the URL:

23 Jun 2011 6:30 AM

Not the same Impressive.  The AQHA Impressive was an Appendix that advanced, foaled in 1969 by Lucky Bar out of Glamour Bars, line-bred Three Bars.  He was a World Champion halter horse and was probably the most all-time popular AQHA stallion.  Impressive bred horses have a very distinct head shape and ears.  At one time, before HYPP became evident, Impressive bred horses were in very high demand and commanded a very large price.  Today, you almost can't give one away.  While tere is no doubt they are exquisite to look at, HYPP is not something most people want to mess with.

23 Jun 2011 8:02 AM

@ rapture

"In the good ol' days...If a horse bled, it didn't run, and it sure as hell didn't breed."

Yeah, right they didn't breed bleeders.  How do you think "Bleeding Childers" aka Bartlett's Childers, got his nickname?

Bartlett's Childers sired Squirt who sired Marske who sired Eclipse.

This is a problem that's been ongoing since the 1700s.

23 Jun 2011 7:25 PM

Allowing animals with one copy of the suspect gene to be bred is the way you reduce incidence over time, and yet retain a broad gene pool. An animal with one Normal and one Suspect Gene when bred to a normal (no copy of the disease gene), will produce ALL disease free off-spring carrying at least one normal gene. Those off-spring must be bred to a Normal X Normal mate to further reduce incidence of the disease. There will be more Normal X Normals in the second generation.

If the off-spring are significantly better than their parents, they will replace their parents to move the breed forward. That's breeding to control disease.

If the Quarter Horse problem is spreading, then it seems there may be variables, --other genes in play, that contribute to affliction. Genetics is often not as simple as we'd hope. And maybe that variable is also positive since it makes for a wider gene pool. Perhaps too, the gene identified as related to the QH problem, also interplays with other genes. Many time conditions involve many genes, along with  environmental pressures that contribute to expression. Environment (which can include triggers that set off the disease gene) factors in over 65%. We are not locked into our genetics, but are dynamic.

Keep trying to understand what you are looking at. Today we're seeing more genuine talent than ever before with the reduction of steroids and pain killers. Definitions change all the time, but the best breeders will consider all information when making their decisions. The market-that short term kick-is already changing in their expectations. There will be no profit if the world turns its back on US horses. The real race for US based breeders will be to catch up with world expectations so to be competitive.  

24 Jun 2011 5:13 PM

Finally it seems that there's a cpmpelling reason to stop the insanity of breeding to defective individuals.   The best horses should win, not just the best medicated.   Maybe if the breed has to get stronger, we can return to real racing.   I just noticed the Mother Goose is now 1 1/16 miles- WHY?   Why can't stakes class horses run any farther?   In the interest of faster maturing horses, diversity was bred out, and most horses today have a very limited range.   In the good old days, when horses were bred to beat anyone at any distance, horses like Man o' War, Citation, Exterminator, Kelso and Forego could race in top company over any distance, no excuses, and a Horse of the Year really had to prove himself.  There's so much inbreeding to Raise a Native and Northern Dancer that their own defects- limited stamina and unsoundness- have become the norm for the breed.   Is anyone else excited about Animal Kingdom's potential as a complete outcross?

25 Jun 2011 4:53 PM

realquiet- "It's a case of the pocketbook being more important than the individual horse or the overall health of the breed."  

That sums up the AQHA.  Yet there are those who think the Jockey Club should follow the AQHA in allowing AI, IVF & ET.  Can you imagine Rachel Alexandra or Zenyatta with multiple ET foals in the same year?!  

The Jockey Club has done their best to preserve the integrity of the breed.  Should they implement a policy for bleeders?  I think it's time.  I've always thought the Germans have it right.  A horse should have to DO something before it is allowed to reproduce itself.  And do it unmedicated.

26 Jun 2011 7:43 AM

Disregard newsline2's genetics "lesson" as it's simply incorrect.

julieo- Animal Kingdom is not "a complete outcross". Can you read a pedigree, and do you understand the meaning of the term, complete outcross"? For openers, Animal Kingdom is 4x4 Lyphard (by Northern Dancer who, in turn, is out of a Native Dancer mare).

The above (newline2's, and julieo's) are examples of misinformation that often appears on the internet-particularly in blogs such as this. Not only do many of the BloodHorse blog authors fail to edit posts received, they also later fail to respond (comment) on the misinformation posted on their blogs. Opinions are one thing, but erroneous facts are quite another.    

26 Jun 2011 3:16 PM

Hello scepter, thank you for your thoughts over the years and appreciate the feed back. Feel free to provide data and links to BH pages to help provide examples to points, has many blog posts that address misinformation and common urban myths.

Ian Tapp is a great resource at for explaining such challenges.

27 Jun 2011 12:57 PM

Dear aspradling,

I infer from your comment that you work for the BloodHorse. I completely agree that Ian (and the others at TrueNicks) is a great resource for matters such as the one (newsline2's comments) I raised. Unlike almost all your blogs, the Truenicks' blog will often respond critically (and politely) to comments posted on their blog that contain eroneous information. Yes, I could certainly "explain" (correct) the errors found in newsline2's discussion, but the effort would prove too time consumming. Rather, perhaps you should take your own advice and contact Ian-and since he's a TrueNicks (?BloodHorse) employee, you might offer him additional compensation to "police" and later clarify BloodHorse web posts on topics such as these.    

27 Jun 2011 1:36 PM

scepter: Thank you again for the feedback, the comments on are moderated for approval, but are not typically edited since everyone has a right to speak their thoughts. I can certainly attempt to interact more in the blogs.

I would enjoy hearing from you at aspradling[at] for concerns with the blog stable on

28 Jun 2011 12:00 PM

Lots of good comments here.

Sceptre, regarding Dr. Palmer's comment on the study. The study had been out for a while but was published by a relatively small veterinary journal (so I'm told) and had not been read by many people attending the medication summit. The study was introduced by Dr. McVeigh during a panel discuss and it seemed like news to a lot of people. There is also a difference between scanning the conclusions of a study and reading it to analyze the sampling and methodology. Without putting words in Dr. Palmer's mouth, I took him to mean he had not had the chance to sit down and delve into the details of the study.

I would be interested to hear what you learn from any of the study's authors.

And to newsline2, I am no expert in genetics but your explanation sounds like an oversimplification of a complex problem. Certainly with EIPH, which is seen--at this point--to be a condition influenced by multiple genes.

06 Jul 2011 10:48 PM

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