A horse race is a contest of speed among horses that either are ridden by jockeys or pull sulkies and are driven by drivers. The word race is also used to describe other contests of speed, such as a nail-biting football game or political debate.

In a horse race, the winning horse is the one that crosses the finish line first. The other horses are ranked according to their finishing position. A horse can be backed, or a bet made on its chances of winning. Some races are handicapped, in which case the top-ranked horses get a higher payout than the lower-ranked ones. The race is often marked by a roar of fans and the sound of horses galloping through the air.

Before a race, the horses in the field are injected with Lasix, a diuretic that is noted on the racing form. This is done to prevent pulmonary bleeding, which hard running can cause in many horses. When a horse bleeds, it can be dangerous and unsightly. It can also cause a horse to lose water and minerals, and thus lose its stamina. For decades, nearly every thoroughbred in the United States has received race-day Lasix. The drug’s diuretic effect causes the horses to unload epic amounts of urine—twenty or thirty pounds of it.

At the starting gate, the horse Mongolian Groom balked. Bettors look at a horse’s coat in the walking ring before a race and consider whether it looks bright, rippling with sweat and muscled excitement. If a horse balks, it is feared to be frightened or angry. This is bad for business.

The reason a horse balks is that it feels overworked, tired or otherwise not ready for the race. The problem is that the race — even an ordinary standardized heat — requires enormous exertion from the animals, and horses who aren’t fit can die in the process.

A horse’s lungs can be strained or punctured by collisions with other horses, other obstacles and the track itself. The horses’ spines can break, and their legs can be fractured or dislocated to the point where skin is the only thing keeping them attached to the rest of the body.

Those injuries can be very costly to the industry. When a horse is injured, its chances of finishing the race are diminished and the wagers it attracts aren’t as large. This diminishes the financial returns for owners and trainers, and it can also lead to a shortage of races to run. The result is that a lot of horses are pushed past their limits, and, according to the activist group Horseracing Wrongs, a great many of them — PETA estimates ten thousand American thoroughbreds annually — end up dead at the track.