EVOLVING UNDERSTANDING IN EXERCISE-INDUCED PULMONARY HEMORRHAGE

Exercise‑induced pulmonary hemorrhage, EIPH or “bleeding”, has been recognized for centuries. The true cause of this disease was misunderstood until modern diagnostic tools revealed that bleeding actually comes from the lungs, not the nose. For much of its history, the condition was understood as the rare and dramatic episodes of nosebleeds (epistaxis) after intense work, and bleeding was seen as a one-off, colorful event in an otherwise healthy horse.

With the advent of the tools of endoscopy and bronchoalveolar lavage (“lung wash”), it became clear that bleeding from the nose represents a relatively rare occurrence of a much more common lung condition. Today, EIPH is recognized as a widespread, seemingly silent feature of equine athletes, with studies finding it in up to 95% of Thoroughbred racehorses.