Only 15 months after it began, the jockey career of Katie Clawson has come to an end, at least temporarily, perhaps permanently. Clawson, 20, said Friday she would no longer ride races and was resuming work as an exercise rider. Clawson said she had taken a job galloping horses for trainer Mike Maker. A five-pound apprentice, Clawson was the leading rider at the ongoing Indiana Grand race meet when she was thrown from a mount during morning training, suffering a concussion. Clawson tried to ride on one subsequent card but took off her mounts after one race and has not returned since. She said Friday that she hadn’t officially been cleared by doctors to ride, but that her medical situation only expedited a plan she had hatched some time ago. “The concussion made it more immediate, but this has been a plan of mine for awhile, that at the end of the Indiana meet or the end of this year, I was going to go back to galloping and stop riding races,” Clawson said. “I decided what I wanted to do on the racetrack and what makes me happy. I’ve prayed about this a lot, talked to a lot of people and gotten advice from the people I trust. It’s not a letdown or a disappointment for me.”   Clawson, who didn’t rule out a return at some point to race-riding, set a goal years ago of becoming a jockey, but said direct experience with the vocation had changed her perspective. “My personality did not exactly line up with the jockey lifestyle. I’m happy with less of a spotlight, more time with my family, less of the perception of other people. All that wasn’t something I experienced before. I was able to fulfill my dream, but I just found out what makes me happy. You don’t have a way of testing that out without doing it.”