Physical Danger
Most people struggle to handle an excited puppy. Equestrians have to wrangle horses—giant, nervous animals that can throw you, fall on you, and/or collapse your chest with one well-placed kick. They're made of some tough stuff.
Most horse-related injuries occur when you fall off or are thrown off a horse (source). The consequences of this can range from light bruising to horrible fracturing to—on rare occasions—paralysis or death. Concussions are common, as are wrist and ankle injuries (source).
So be sure you pack your helmet when you're heading off to college.