The Return of October

The Return of October is a 1948 American comedy film starring Glenn Ford and Terry Moore. The film was directed by Joseph H. Lewis.

Now living with wealthy Aunt Martha, the girl is convinced that Uncle Willy has been reincarnated as a horse named October. A psychology professor, Bentley Bassett, writes a book about Terry, which is used in a sanity hearing against her by crooked relatives who want dying Aunt Marthas money.Bassett uses college funds to help Terry buy the horse. They enter October in the Derby, where other bettors join them in cheering Uncle Willy to victory. ........

Source: Wikipedia