Truthfully, a degree in some sort of Equine Science or Equine Studies might limit your future options. Take it from someone who knows first hand. I chose a college solely because it had an Equine Science program. I wanted so badly to be an Equine Veterinarian. I couldn't imagine myself doing anything else with my life other than working with horses. However, once I started college as an Equine Science major, I realized what Equine Science really was. It was a bunch of watered down science classes (the ones that the non-science majors normally take) supplemented by a few basic equine management and training classes and large animal science classes. Horses are something you can't really learn about in a semester and in a classroom setting. It's something you really need to DO and EXPERIENCE before you truly understand them. And, as someone who has owned horses and taken lessons and worked in stables for many years I knew most (if not all) of the stuff that was being taught in the class room. Things like basic anatomy, nutrition, daily care, first aid, and training techniques are things that most long-time horse owners are well-read and well-practiced in already. Halfway through my freshman year, I switched my major to biology. I ended up taking all the courses I needed to best prepare me for vet school such as microbiology, virology, comparative anatomy, physiology, genetics, molecular biology, immunology, and histology (all of which were NOT a part of the equine science major). Then I took some of the equine classes as electives.
I know you plan to start a boarding or lesson facility, not become a vet, but it's really the same situation. I think you might find that a program geared towards an equine education might limit you. You may be better off attending a school with an equine program so those courses are available to take as electives, but being a business major. I bet you probably know quite a bit about horses and have a lot of experience with horses already, if you're so determined to spend the rest of your life working with them. What you really need to know is how to start and run a business. And that way, if you change your mind about what you want to do down the road, or if you need to work somewhere else to supplement your income, it would be easy for you to use that degree in other areas.
I eventually decided that I did not want to pursue a higher degree, at least not at this point in my life, because money is a limiting factor. I cannot afford grad school and I cannot afford to get a veterinary degree. But because I have a biology degree instead of just an equine degree, my career options were wide open. I was able to get a job working in a veterinary diagnostic laboratory, and I love what I do now! If I had not switched my major to biology, I would not have been qualified for the job I have now.
However, if you are not looking for a full on college degree, then a certification in equine massage or something else along those lines would be a great idea. You will still need some other income to supplement until you establish yourself in the business, but if it's what you want to do, it could be a good thing and you could eventually support yourself on it or use it for some extra income in addition to whatever else you decide to do. I still stand by what I said before and recommend that you try to take a few business courses and learn how to start and run your own business if that's what you plan to do.