Barn owner/manager, breeder, some of the more rural ares of the US let you keep horses if you teach agriculture (yes my school was one of them....our school owned something like 500 head of cattle, 12 sheep, 3 llamas, 8 or 9 pigs, and a horse)
Less obvious: Horse Photographer believe it or not. Takes horse know how to get a horse to pose for a picture but some people apparently are able to make a career of it!
Horse journalist. Has to hang out with those horses and horse people.