A major study of the incidence of exercise-induced pulmonary hemorrhage (EIPH) in performance horses could benefit all horses,
and such a study might soon be undertaken if a research committee of prominent equine veterinarians determines the study should
go forward and outlines its scope.
The United States Eventing Association (USEA) appointed a research panel that would set guidelines for the potential study
and review previous work on EIPH. If the committee decides the study should proceed, it will prepare a formal proposal and
talk with the USEA and other research-funding groups to commission the work.
Ready to compete: Eleanor Green, DVM and president of the American Association of Equine Practitioners, with her horse, Miss
Rivum N Blues, before competing in the working hunter class at the Gold Coast Quarter Horse Circuit in Tampa, Fla., about
three years ago.
A. Kent Allen, DVM and owner of Virginia Equine Imaging in Middleburg, Va., who lectures and writes on sports medicine, lameness
and diagnostic imaging, is the committee chairman.
Working with him on the panel are Eleanor M. Greene, DVM, chair of the Department of Large Animal Clinical Sciences and chief
of staff of the Large Animal Veterinary Medical Teaching Hospital at the University of Florida's College of Veterinary Medicine;
Catherine Kohn, DVM, professor in the Department of Veterinary Clinical Sciences at The Ohio State University; and Mark Revenaugh,
DVM, who practices at the Equine Performance Institute in Mulino, Ore.
The USEA wants to expand what until now has been limited knowledge on the incidence of EIPH in performance horses. Research
to date has been done mostly on Thoroughbred racing horses, the majority of which have some blood in the trachea after racing,
but horses of all kinds engaged in any strenuous activity are susceptible, Green tells DVM Newsmagazine.
"In racehorses, observable bleeding from the nostril after strenuous exercise has been reported since the 17th century," says
Green, president of the American Association of Equine Practitioners (AAEP).
"While the incidence was low, only after endoscopy was used to detect bleeding within the lower airways was EIPH in racehorses
documented. Studies in event horses using endoscopy immediately after strenuous exercise would document their incidence of
EIPH. But the incidence of fatal pulmonary hemorrhage is very rare."
Studies show fundamental differences between the heart and lungs of horses and other mammalian species, Green says.
"It is known that during exercise horses have unusually high pulmonary arterial blood pressures." High pressures in the heart,
and thus the lungs, are related to the inability of the horse's heart to relax quickly enough between beats, she explains,
adding that mechanisms continue to be studied in various research laboratories.
Based on the studies with racehorses, "any strenuously exercising horse should be susceptible to EIPH," Green says.
If the committee decides the EIPH study should proceed, which Green believes is likely, just who would perform it, how much
it would cost and how long it would take are yet to be determined.
"Whoever is best qualified and passionate about the study" would carry it out, Green says. "Ideally this would be a broad,
collaborative study involving a team of researchers, each bringing something important."
The team could include those with knowledge of the sport and event horse, clinical researchers to perform field studies, epidemiologists,
basic science researchers in various disciplines and possibly researchers in the human field engaged in related research,
according to Green.
What's the ultimate goal? "Certainly it would be ideal to determine the incidence of EIPH and fatal pulmonary hemorrhage
in event horses, identify risk factors and causes and ultimately discover effective treatments and strategies for prevention,"
The research would take place in logical steps — some in sequence, some in tandem.
"The first would be a literature search, amassing all data currently available to help direct the most efficient and effective
research path and avoid duplication of effort," Green explains.
Determining the incidence of EIPH in event horses, currently unknown, "would entail endoscopic examinations following exercise
of horses in competition. Epidemiologic studies could help clarify the incidence of fatal hemorrhage and explore risk factors.
And, laboratory studies would be required to look at the mechanisms of disease and treatment and prevention strategies," Green