There is no specific degree you need to get to become a horse trainer or riding instructor. However, a degree in Animal Science will give you a good understanding of the physiology, behavior and management of horses. There are some schools that train riding instructors or certify them such as the Certified Horsemanship Association
. Most horse trainers learn this skill by working or apprenticing with older established horse trainers. If you are interested in a career as a horse trainer, I would suggest you contact a local trainer and volunteer to work with them for a week or so to get a good idea of what is involved.