A Day at the Races (1937) on Netflix

Town villain Morgan has his sights set on taking over Judy's sanitarium and turning it into a casino. Aiding Judy in saving the sanitarium are Dr. Hugo Hackenbush, a horse doctor illegally employed as the sanitarium director; Tony, a helper at the sanitarium; and Stuffy, a jockey formerly employed by Morgan. Judy's boyfriend, Gil, a singer, has invested all his money in Hi Hat, a race horse he hopes will win enough to pay off the sanitarium debts. After Gil figures out the horse is a jumper and not a racer, the boys try to win a major steeplechase race, while Morgan and his men try to prevent the horse from getting onto the race track. Obligatory appearance by Margaret Dumont as the wealthy hypochondriac who might also save the santitarium from financial ruin.