Nancy McKeon (The Facts of Life), in one of her first cartoon roles, essays the title character, an orphaned pup who loses her mother, Dutchess (June Foray), when the latter is shot by a farmer mistaking the two dogs for sheep-killing coyotes.
Unfortunately, the complete three-parter isn't available. All that we have is a nearly 10 minute sampler that includes the opening credits used in all three episodes. Alan Young narrates.
Other voice talent includes Michael Bell, Janet Waldo, Michael Rye, Walker Edmiston, and Frank Welker. I think it's available on DVD somewhere, but I'm not certain.