The Adventures of Rusty (1945)
The Adventures of Rusty is a 1945 drama film, the first in the "Rusty" series of children's films. The series of eight films were made in the 1940s by Columbia Pictures with stories centered around Rusty a German shepherd dog. The film is notable for featuring the famous Ace the Wonder Dog as Rusty, the only appearance by Ace in the Rusty films.
More at Wikipedia.