
09/08/2025
When your horse is exercising, they have an increased oxygen intake and increased blood flow. This pushes their heart rates to upwards of 220 bpm, with their blood flowing through their lungs at a staggering rate of 75+ gallons per minute!
Increased blood flow leads to increased blood pressure inside the pulmonary capillaries. On the outside of the pulmonary capillaries there is a strong opposing vacuum pressure caused by the horse breathing up to 120 breaths per minute (one breath every half second). Together these opposing forces can cause small tears in the capillaries resulting in blood spilling into the airways.
This is called exercise induced pulmonary hemorrhage, more commonly known as EIPH.