EIPH: Every Racehorse's Concern

EIPH or Exercise Induced-Pulmonary Hemorrhage is a common concern among horses who work out at high intensities. It is no surprise that 80% of thoroughbreds suffer from EIPH. The stress of horse racing causes the blood vessels in the lungs to rupture leading blood to pass into the airways. This happens because the walls of the blood vessels in the lung are thin and weak and cannot take twice the amount of blood pressure that accompanies any intense physical activity. The pressure is greatest in the upper lung and hence bleeding almost always occurs here. The force that impacts this area as the horse lands on its forelegs also adds to the pressure.

In a study in Australia done by Kenneth Hinchcliff of the Veterinary Clinical Sciences at Ohio State University, it was found that racehorses who suffered from serious forms of EIPH finished 4.36 meters behind the winner. This is actually the first scientific study that directly linked EIPH to the poor performance of a horse at the races.

EIPH, being a progressive disease, worsens with rigorous training and as the horse ages, regardless of gender. The overall performance of a horse is significantly compromised as more and more tissues in the lungs are inflamed resulting to the formation of scar tissues. As scar tissues build up, the ability of the lung to ventilate is decreased. As a result, less oxygen becomes available in the bloodstream.

During exercises when the horse is in need of more oxygen, the scarred lung cannot anymore provide as much oxygen and as such horses become exercise intolerant. During a strenuous exercise where the scarred lung meets the healthy lung, an extra tension occurs in the area making it susceptible to hemorrhage.

This has huge implications for the horse racing industry. Even if thoroughbreds in the U.S. are given Lasix, a diuretic that increases water loss to decrease blood volume and pressure, EIPH is still difficult to control overall since no medication has really been developed specifically to treat it. When a horse is only suffering from mild forms of EIPH, his chances of winning a race increases four times compared to one who is suffering the ailment in its advanced stages.

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