Exercise Induced Pulmonary Hemorrhage (EIPH) more commonly called "bleeders" are horses that bleed from broken capillaries in their lungs after strenuous exercise. This condition has been a known problem in the horse racing industry for hundreds of years, but in spite of the prevalence, very little has been successfully done to treat the condition.
The condition varies in severity with almost all horses on the racetrack being affected at some level. The most severely affected horses will actually bleed from the nostrils, which is where the name bleeders came from. Many horses are affected to a lesser extent, however, with a large portion of them showing bleeding in the bronchus visible with an endoscope after intense exercise. Blood can be found microscopically in the lung field of horses that didn’t show it visibly with endoscope or bleeding from the nose in most cases. Between the three categories statistics say that well over 90% of horses on the track are affected.
Known bleeder horses are typically been treated with a medication called Furosemide, which is also marketed under the name Lasix. Interestingly enough, we do not know exactly why horses given Lasix have improved symptoms. Lasix is a diuretic that is commonly used in heart disease, and many older people have been told it is a “water pill”. In racehorses, it is thought that perhaps the fact the medication reduces the bodies fluid volume, is enough that there is reduced pressure at the capillaries in the lungs during exercise, resulting in less capillary rupture and less bleeding.
The problem is that nobody really knows why the medication helps, and horses with no known history of bleeding also tend to have improved performance when given the drug, bringing into question if it is in fact a "performance-enhancing" drug. Again, there is no scientific understanding for why there would be an improvement, though one theory is that horses would sustain a temporary, but significant weight loss due to the loss of bodily fluid resulting in an improved performance at the late stages of the race.
EIPH has also been showing up more frequently in other strenuous equine activities such as barrel racing, which continues to bring this condition to the forefront of our concern. Primarily our concerns are, what is the long term affects to horses’ lungs when they go through repetitive episodes of bleeding? Are long-term consequences like to show up, such as COPD or Heaves, later in life?
The topic has been discussed recently scrutinized as the US racing Coalition has recently announced that they will ban the use of Lasix in 2-year-old grade stakes races. Now the big name horse races that the average person has heard of such as the Kentucky Derby are 3 year old races, and at this time the rule change will not effect those horses, but this change is a big change for the horse industry that has relied on controlling the symptoms of EIPH using Furosemide for many years. Racing horses as 2 year olds is a somewhat controversial concept in itself as horses are far from mature at that age and are more prone to injuries due to the extremely stressful activities, but perhaps this rule change is a start to reassessing the whole industry at that age.
The rule changes to the racing industry will not have an impact on the barrel racing industry, however, the hope is that changes starting in the race industry will drive forward additional research to support healthy ways of managing this condition. Keeping our horses physiologically safe for long-term healthy careers is our primary goal.