Common Injuries and Ailments
EIPH or Bleeding
Exercise-Induced Pulmonary Hemorrhage (EIPH), commonly known as
bleeding, has been known to afflict Thoroughbreds since the early
18th Century. Tom Biracree and Wendy Insinger point out in their
book The Complete Book of Thoroughbred Horse Racing that reference
to bleeding can be found in the name of the early 18th Century
English stallion Bleeding Childers. Subsequently his name was
changed to Bartlett's Childers. Bartlett's Childers is the
great-grandsire of Eclipse, the horse which 80% of all modern
Thoroughbreds trace their parentage.
EIPH is characterized by bleeding from the lungs after strenuous
exercise. According to an article in the UC Davis Center for Equine
Health's The Horse Report, recent studies suggest that anywhere from
70 to 100 percent of horses in racing and training experience EIPH.
It is believed horses experience EIPH because during exercise they
have unusually high blood pressures in the vessels that lead from
the heart to the lungs and this high pressure causes the walls of
the vessels to break and release blood into the airways.
The American Association of Equine Practitioners (AAEP) recommends
for a horse to be declared ineligible to race for a minimum of 10
days after the first incident of EIPH. If a second incident occurs,
recommended ineligibility is 20 days. Ineligibility for at least 60
days is recommended for third and subsequent incidents. After the
third incident it is at the discretion of the track veterinarian in
consultation with the practicing veterinarian and trainer when the
horse is declared eligible to race.
HELPFUL TIPS: EIPH Facts vs. Fiction
Reprinted with permission from the UC Davis Center for Equine
Health.
Fiction:
If you can't see any blood in the nose after exercising, there was
no bleeding (EIPH).
Fact:
Most cases of EIPH occur internally with no external sign of
bleeding. In Japan, researchers analyzed 250,000 racing starts and
found that bleeding from the nose occurred in less than 0.2 percent
of the racing starts. However, in studies using an endoscope, in
which a tube is passed via the nose and the veterinarian looks into
the airways, researchers found that 50-70 percent of all horses that
race experience EIPH at some time. In studies that evaluated airway
cellular debris, results suggest that perhaps 100 percent of
racehorses experience EIPH.
Fiction:
Only Thoroughbreds running flat races experience EIPH.
Fact:
Bleeding can occur with almost any type of severe exercise in
horses, even with draft animals pulling heavy loads. Some horses
pull up and show evidence of bleeding immediately after sudden
exertion (e.g., the start of a Quarterhorse sprint). Some evidence
suggests that bleeding might be more frequent in shorter, higher
intensity events. At UC Davis, horses on the treadmill have bled
severely when simply changing from a trot to a canter.
Fiction:
Lasix will prevent a horse from bleeding.
Fact:
The diuretic Lasix can be legally administered four hours before a
race to horses that have been documented with a history of bleeding.
Although Lasix does lower blood pressures slightly, there is no
proof that it reduces the incidence or severity of bleeding. Several
studies have found evidence indicating that Lasix measurably
improves racing performance; however, it dehydrates the horse prior
to the race, as well as dilutes any drug residues that might be in
the urine. Recent evidence indicates that Lasix causes only a slight
improvement in racing performance.
How do I tell if my horse is bleeding?
In rare cases, a horse may spray blood from its nose while
exercising or after abruptly pulling up. In other unusual cases,
there may be a thin trickle of blood showing from one or both
nostrils up to two hours after a workout. The most common way to
diagnose EIPH is by passing a flexible endoscope into the horse's
airways to view the blood that is being cleared from areas of the
lungs where bleeding occurred. This is usually done one to two hours
following exercise. Over time, repeated EIPH incidences will lead to
changes in lung structure as a reaction to the blood in the airways.
In extreme cases, large areas of the lung's upper rear portion may
consolidate to become unusually solid which may be detectable with
radiographic imaging.
