Horsing Around (1957)

A sequel (sort of) to "Hoofs and Goofs", The stooges are taking care of their sister Birdie who has been reincarnated as a horse. When they learn that her mate "Schnapps", a famous circus horse, is about to be destroyed, they got to the circus grounds to rescue him. The stooges are successful, and Birdie and Schnapps are reunited.