The sport of horse racing has morphed into a spectacle involving thousands of horses, sophisticated electronic monitoring equipment and immense sums of money. Yet the core of the sport remains unchanged: horses compete against one another in a test of speed and endurance, with the first to cross the finish line declared the winner.

But behind the romanticized facade of the sport is a dark world of injuries, drugs and gruesome breakdowns. Horses are forced to sprint—often under the threat of whips and sometimes even illegal electric shocking devices—at speeds so high that they can sustain serious injuries, including hemorrhage from the lungs. And unlike human athletes, they cannot say no: If a horse trainer tells them to race, they must comply.

As a result, racing is one of the most dangerous sports in the world for animals. In addition to the physical toll of running at high speeds, many horses are subjected to cruel treatment and forced to race despite injuries or other mental or emotional issues. Ownership turnover is rampant, and horses are often sold (“claimed”) multiple times over the course of their careers. In a two-month period in 2011, over 2,000 horses were callously sold through claiming races.

In a typical race, eleven horses will break from the starting gate. The field will then begin a long and winding journey around the track, which has been turned into an oval and is usually a distance of a mile or more with at least two turns. The horses will be ridden by jockeys, and the winner will be the one that crosses the finish line first.

At the beginning of a race, the horses will have been injected with Lasix, a diuretic, which will be marked on their racing forms with a boldface “L.” The drug is used to prevent pulmonary bleeding, which can occur when horses run hard and become dehydrated. But it has a side effect: It causes horses to unload epic amounts of urine, sometimes twenty or thirty pounds worth.

The race was set to begin in less than 48 hours, and the horses would need to be fully prepared by the time they ran at dawn. They had to be cooled down, fed, and given a special anti-inflammatory medication called phenylbutazone. They were also pumped with adrenaline to keep them focused and alert, and their nostrils were blocked to make sure they wouldn’t be startled by the noise of the crowds.

Once the gates opened, it was clear that the colt War of Will was going to take an early lead. As the horses reached the clubhouse turn, he moved into the lead, with McKinzie and Mongolian Groom following closely behind him. Horses are prey animals, and being at the front of a pack can be extremely stressful: They are kicked, pushed, and pinched. If they are not allowed to flee, they will fight to survive.