Bad Luck Blackie (1949)

Watch Bad Luck Blackie: A little cat is being mercilessly tormented by a mean bulldog until one day he meets a black cat who offers a bad-luck service. Whenever the little cat blows a whistle, the black cat comes out, and the bulldog is struck down with an attack of bad luck. Things look bad for the bulldog until he realizes that a cat's color can be changed...