Skipper Learns A Lesson (1952)

Susan, a little white girl, moves into a racially mixed neighborhood. Soon some of the local kids come over and ask her to play with them. She does, but her dog, Skipper, will have nothing to do with such funny-looking children (he says, via the narrator). Soon, however, Skipper accidentally gets some paint spilled on him, and the neighborhood dogs attack him, as they don't want somebody who's "funny looking" in their neighborhood, either. Skipper realizes that his intolerant attitude toward the children was just as bad as his fellow dogs' attitude toward him, and vows to change his ways.