Adventures of Rusty (1945)

Fearing that his recently acquired stepmother, Ann Dennis, is competing with him for his father's affections, and saddened by the death of his dog, young Danny Mitchell, in the first film of the long-running "Rusty" series, seeks consolation in the companionship of a ferocious, German-trained police dog, Rusty, brought to the U.S. by a returning World War II veteran. The stepmother, with tender understanding, eventually wins Danny over while Danny pacifies his new dog.