(Originally published in the June 25, 2011 issue of The
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By Eric Mitchell - @EJMitchellKy on Twitter
A 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.