The Boy From Indiana(1950)

Happy-go-lucky aspiring sportswriter Lon Decker from Indiana who has aspirations of becoming a sportswriter meets the shrewd and larcenous old man, "Mac" Dougal during his wandering. Mac likes to ensure his bets on Quarter-Horse races by doping a horse or two here and there. When Lon finds out Mac intends to fleece wealthy rancher Zelda Bagley he sets out to stop him.