Study Examines EIPH and Racing Performance

The study found no association between low-level EIPH (Grades 1, 2, and 3) and long-term racing performance.

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Researchers recently found no link between the vast majority of horses who suffer from exercise-induced pulmonary hemorrhage (EIPH) and long-term racing performance, although they did find that the small percentage of horses who suffer severe EIPH see their long-term performance impaired.

The study was conducted by some of the world's foremost experts on EIPH, including Kenneth Hinchcliff, BVSc, PhD, Dipl. ACVIM, and Paul Morley, DVM, PhD, Dipl. ACVIM. Hinchcliff and Morley were two of the authors of a landmark 2009 study that concluded pre-race administration of furosemide (Salix, commonly called Lasix) decreased the incidence and severity of EIPH.

That study examined horses racing in South Africa in races carded for the study. In this latest study, the team acknowledged EIPH can impair short-term race performance but examined the relationship between EIPH detected on a single occasion and long-term athletic performance in Thoroughbred racehorses.

In the study, 744 Australian Thoroughbreds a underwent a single tracheobronchoscopic examination to determine presence and severity of EIPH in 2003. The study then kept tabs on the racing performance of each of these horses.

Following retirement of all the study horses from racing, career performance data, including duration, earnings, starts, wins, and placings, were abstracted from a commercial database. The association between presence and severity of EIPH in the single tracheobronchoscopic exam and individual performance variables were analyzed.

In the tracheobronschocopic exams, 45% of the horses showed no EIPH while 55% of the horses showed some level of EIPH, which is graded on a 5-point scale (0-4). Grade 4 is the most severe level, typically associated with epistaxis (bleeding from the nostrils). Only 1.7% of the examined horses showed this level of EIPH. There were 273 horses found at Grade 1 EIPH (36.7% of all horses examined), 101 at grade 2 (13.6%), and 25 at grade 3 (3.4%).

The study found no association between low-level EIPH (Grades 1, 2, and 3) and long-term racing performance. The racing performance of horses examined who showed Grade 4 EIPH was impacted, suggesting "that the severity of EIPH commonly associated with epistaxis adversely affects either the horse's opportunity to race or physiologic capacity to race."

The study concluded, "There is no association between EIPH Grades 0 (no EIPH), 1, 2, and 3 and long-term racing performance."

The study noted that this conclusion was based on a single endoscopic evaluation. It suggested more study is needed on why horses with Grade 4 EIPH see their long-term performance suffer.

The study, "Prospective study of the association between exercise-induced pulmonary haemorrhage and long-term performance in Thoroughbred racehorses," will appear in an upcoming issue of the Equine Veterinary Journal.

Originally published on BloodHorse.com.

About the Author

Frank Angst

Frank Angst is a staff writer for The Blood-Horse magazine. An American Horse Publications three-time winner in best news story category, Angst has covered horse racing for more than a decade. Angst spent ten years at Thoroughbred Times, where he earned awards as that magazine’s senior writer and helped launch Thoroughbred Times TODAY. Besides covering horse racing, Angst enjoys handicapping. Angst has written about sports for more than 20 years, including several seasons covering a nationally ranked Marshall Thundering Herd football team.

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