If you're serious about working with horses for a living, the best route to go IMO is to go to a school where you can major in business and minor in equine studies and then also apprentice yourself to a trainer or find a working student position in your discipline.
Here's my reasoning:
Many horsepeople give up on making a living as horsepeople because they're terrible businesspeople, not because they're poor horsepeople.
A degree in Equine Studies, without customer service skills, people skills, computer skills and business skills will only get you a job saying "Would you like fries with that?"
People chose trainers based on reputation, word of mouth, results in the show ring and with problem horses. Your brand new Equine Studies degree won't give you any of that, and your new diploma won't bring you training clientele.
The college education, combined with the real world experience is the better way to go.