As Kentucky Derby Nears, Last Year’s Deaths Cast Long Shadow

To make matters worse, horses were frequently overworked, and when they dropped dead, their bodies were often left rotting on the streets for several days before being dismembered and removed, posing a further health risk. By the 1880s, fifteen thousand dead horses were being removed from the streets of New York City each year.

the trainer took pains to make the schooling feel like fun. When a horse got tired, the trainer took him off the track. If a mount got bored or restive, the trainer never forced him to continue or drove him "through the pain."