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Exercise Induced Pulmonary Hemorrhage

Exercise Induced Pulmonary Hemorrhage (EIPH) also known as "bleeding" or a "bleeding attack" has been known to occur in horses that engage in short periods of strenuous exercise. These horses usually include Thoroughbred and American Quarter Horse racehorses (incidence of 50-75%) and Standardbred racehorses (incidence of 40-60%), but it may also occur in jumpers, polo ponies, and draft horses that pull competitively. [1] It appears rarer in stallions than mares or geldings,[2] but it is associated with airway inflammation and increasing age.[3]

The affliction occurs when blood enters the air passages of a horse's lung, due to fractured lung capillaries. Blood is sometimes evident discharging from a horse's nostrils (epistaxis), however, this usually only occurs in 5% of bleeders.[1][4] If a horse does not exhibit epistaxis but is suspected to have EIPH, an endoscopic exam is performed soon after the horse is exercised.

It is believed that nearly all horses experience it (when exposed to strenuous exercise)[5] and it has the potential to decrease lung function over time. However, there are no documented cases of bleeding in wild horses when rounded up [6] with helicopters from mountain tops in pens miles away. Neither is there any mention of bleeding in the National Historic Research Study on the Pony Express [7] when horses were galloped 10 to 15 miles between relay stations and sometimes through Indian country.


The drug commonly known as Lasix (Furosemide) has been used to prevent the condition, although it does not work in 50% of cases[1], and it is banned in some countries. Other treatments that have been used include bronchodilators, coagulants, and estrogen. A product called Equiwinner claims success in 99% of bleeding cases. It is introduced to the horse via a patch, using electrical signals to restore the horses electrolyte balance.


  1. 1.0 1.1 1.2 Riegal, Ronald J. DMV, and Susan E. Hakola DMV. Illustrated Atlas of Clinical Equine Anatomy and Common Disorders of the Horse Vol. II. Equistar Publication, Limited. Marysville, OH. Copyright 2000.
  2. Hillidge CJ, Whitlock TW, (1986) "Sex variation in the prevalence of exercise-induced pulmonary haemorrhage in racing quarter horses" Res Vet Sci. 1986 May;40(3):406-7
  3. Newton JR, Wood JL, (2002) "Evidence of an association between inflammatory airway disease and EIPH in young Thoroughbreds during training" Equine Vet J Suppl. 2002 Sep;(34):417-24
  4. "Exercise-induced Pulmonary Hemorrhage". The Merck Veterinary Manual. 2006. http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/121312.htm. Retrieved 2007-07-10. 
  5. AAEP Newsroom September 1999, at [1], accessed at 1945 on 11th July
  6. The Cloud Foundation Blog, Independent Humane Observer Elyse Gardner: Preliminary Report and Update at [2].
  7. Pony Express Historic Resource Study Chapter Three ORGANIZATION AND OPERATION OF THE PONY EXPRESS, 1860-1861 at [3].


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