EIPH and the racehorse
EIPH frequently occurs in racehorses at intense speed or exertion and is associated with decreased health and poor performance.
It is known to occur in more than 75 percent of Thoroughbreds, with a somewhat less frequent occurrence in racing Standardbreds
and Quarter horses. It is also seen in other horses at high performance (barrel racing, cutting, steeplechasing, three-day
According to Ken Hinchcliff, BVSc, PhD, "EIPH is caused by the rupture of alveolar capillaries, secondary to exercise-induced
increased transmural pressure—a pressure difference between the interior of the capillary and the alveolar lumen. If the transmural
stress exceeds the tensile strength of the capillary wall, the capillary ruptures, dumping blood into the airways and interstitium.
The proximate cause of alveolar capillary rupture is the high transmural pressure generated by positive intracapillary pressure
(largely attributable to capillary blood pressure) and the lower intraaveolar pressure (generated by negative pleural pressure
associated with inspiration)."
This is shown by blood in the tracheal lavage or bleeding from the nostrils (epistaxis) soon after exercise or blood hemorrhaged
into the airways up to one or two hours after exercise. EIPH can recur, with subsequent inflammation of the airways and interstitium
and development of fibrosis and alteration of tissue compliance.
Furosemide is a diuretic that decreases plasma volume, cardiac output and, therefore, pulmonary vascular pressures, reducing
the incidence of EIPH up to 50 percent in some studies.1 Hinchcliff and colleagues, in a study of 152 Thoroughbreds racing in South Africa, showed that the endoscopic severity of
EIPH on a five-point scoring system was less severe after furosemide administration, with no animals having a score of 3 or
4.2 Of the horses scoped after two races, 57 percent of those that had been given furosemide had EIPH with a score = 1, while
79 percent had EIPH scores = 1 after saline (placebo) administration. Results of the study indicate that pre-race administration
of furosemide decreases the incidence and severity of EIPH in Thoroughbreds racing under typical conditions in South Africa.
The furosemide paradox
"Here in the U.S. and Canada, we generally allow a single type of anti-bleeder medication on race day known as Salix (furosemide),"
says Alex Waldrop, chief executive officer of the NTRA. "Some states in the U.S. also allow adjunct bleeder medications. These
medications are administered for the purpose of controlling the incidence and severity of EIPH. Salix is administered in accordance
with state regulations that strictly control the amount and timing of administration. Post-race testing is used to confirm
compliance with these regulations. In terms of national uniformity across America's 38 racing jurisdictions, we have it when
it comes to race day administration of Salix."
"Some in the industry believe that regulators should focus on better testing for designer drugs and harsher penalties for
those who use them—and leave Salix alone," says Waldrop. "But that view is countered by those who point out that the public
at large is not capable of distinguishing between illegal drugs and permitted race day medications—they are all viewed negatively
in today's society."
Some feel that if we could get rid of all the illegal drugs and drugs that are harmful, then furosemide would be less of an
issue. It is an appropriate therapeutic medication. To compare furosemide with anabolic steroids in other sports is inappropriate.
Furosemide with its known therapeutic benefit is a medication that everyone within the sport, including the wagering public,
knows is given. It's even noted on the Racing Form.
But there is current concern, even as raised by the Congressional legislation drafted in May 2011, to ban "performance enhancing"
race day medication and to exclude the use of furosemide in Thoroughbred racing in the future.
"According to industry sources, in the U.S. about 95 percent of horses run on Salix and/or some other anti-bleeder medication,"
says Waldrop. "This is because there are no requirements that horses first bleed before an anti-bleeder medication is administered.
Some administer anti-bleeder medication for its diuretic effect that is thought to improve performance because of weight loss
and other reasons. Long ago, we determined to end the debate whether Salix and related adjuncts are performance-enhancing
by allowing all to have access to the medication, and thereby level the playing field.
"Because of this practice of widely administering prophylactic doses of anti-bleeder medication, the incidents of exterior
bleeding are very rare in this country," Waldrop says. "On the other hand, no one knows for sure how many horses would bleed
but for the prophylactic dosage. For some, the idea of a race day medication—even one legally administered by a qualified
veterinarian under regulatory controls—is unacceptable. For others, administration of Salix is necessary to ensure that we
are looking out for the welfare of the horse.
"Many think our policies should be based on science and the best interests of the racehorse," says Waldrop. "Others believe
strongly that no horse should run if it needs or is given medication to do so. Still others believe that while science is
important, other considerations such as public support for drug-free competition should be factored into the equation when
considering race day medication. Some say it enhances performance, while others assert that it merely allows a horse to run
to its true form."
Waldrop says that another area of disagreement is in the need for international harmonization. "Some believe that North America
needs to be in step with the rest of the world on its medication policies," says Waldrop. "Others believe that we've got it
right, and it is foreign jurisdictions that should move toward our policies and treatment programs for horses with EIPH."