Editor's Note: The Jockey Club believes that horses should compete only when they are free from the influence of medication. The following essay, written by Matt Iuliano, the executive vice president and executive director of The Jockey Club, provides insights into a recent study pertaining to exercise-induced pulmonary hemorrhage (EIPH) and long-term racing performance.
A team of highly respected, international researchers and scientists recently found that in 98% of horses they studied there was no association between exercise-induced pulmonary hemorrhage (EIPH) determined after an endoscopic examination and long-term racing performance.
The findings challenge some long-held opinions in North American racing, including the contention that the use of the diuretic furosemide — sold under the trade name Salix and commonly known as Lasix — is necessary to ensure the long-term careers of equine racing athletes.
The study, “Prospective study of the association between exercise-induced pulmonary haemorrhage and long-term performance in Thoroughbred racehorses,” was conducted by Kenneth Hinchcliff, B.V.Sc., Ph.D., a longtime researcher of EIPH and professor of veterinary science at the University of Melbourne in Australia, and Paul S. Morley, D.V.M., Ph.D., professor of epidemiology at Colorado State University.
It was published online in the Equine Veterinary Journal this spring.
In 2003, those horses had been examined for EIPH and were the subjects of a study into how EIPH affected performance in a single race. For their latest report, the researchers reviewed the entire careers of those horses to determine how their EIPH status affected their racing records.
EIPH is graded on a scale of 0 to 4, with 0 indicating the lowest, or no, indications of EIPH on endoscopic examination and 4 being the highest, often including epistaxis, or bleeding from the nostrils. The original Melbourne study found that horses with either no indication or the slightest indication of EIPH had better finish positions. Horses with mild to more moderate indications of EIPH were more often associated with impaired racing performance in the single race that was studied.
The latest study goes beyond a single race to look at entire racing careers.
Whereas the first study found that horses with EIPH grades greater than 1 had impaired racing performances, this latter study found no statistically significant difference among horses with EIPH graded from 0 to 3 in terms of:
- Duration of careers on the racetrack,
- Number of wins per start and,
- Number of placings per start.
Only those horses with the most severe EIPH of grade 4 (1.7% of the population) had a significant reduction in lifetime racing performance.
When the data was grouped, the authors reported that horses with EIPH scores of 2, 3 and 4 started an average of 2.8 fewer times during their lifetime when compared to horses with EIPH scores of 0 and 1. However, they noted the difference in lifetime starts was highly influenced by the low number of race starts in horses with EIPH graded as 4.
Many of the horses with EIPH graded as 4 were retired from racing early on, which reduced the average number of lifetime starts for any group that included those horses.
The lifetime racing performances of horses with EIPH that continued to race indicate these horses were successfully managed over a productive racing career in a jurisdiction where furosemide was not permitted.
Reviewing all the data, the researchers in the most recent comprehensive study concluded:
“The lack of significant associations between the most common forms of EIPH and long-term performance can be interpreted as indicating an absence of important clinical, physiological, or management factors that limit performance in these horses.”
With the latest research showing that less than 2% of the Thoroughbred population may have impaired lifetime racing performance attributable to EIPH, it is increasingly difficult to reconcile 95% of all North American starts occurring after the race-day administration of furosemide.
As The Jockey Club stated in 2011, overuse of an under-needed medication is not producing a level playing field. In all likelihood, it is doing just the opposite.
We believed then and we believe now that horses should compete only when they are free from the influence of medication.
A prohibition on all race-day medications levels the field.
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