Scattergood Rides High (1942)

When Martin Knox, a friend of Scattergood's who owns a horse-breeding farm, is killed in a harness race Scattergood tells Martin's son Dan that he will send him to college if he forgets about taking over his father's business, which was heavily mortgaged and has been put up for auction after Knox's death. The boy reluctantly agrees, but when he discovers that his favorite horse Starlight is sick, he decides to bring the animal back to health and then enter him in the Governor's Race, whose $5000 prize would enable Dan to pay off his father's mortgage and keep the business in the family.