In general, voice actresses are typically cast as male pups (notably Cree Summer, Kath Soucie, Grey DeLisle, and EG Daily). This makes the irony of Patches' two male friends who berate him for being "girly" all the better.
Also (considering the creators), many from the Recess cast provide voices.
Principal Prickly has moved up to become mayor (in the first season).
Spinelli's the Mayor's son ("A Nightmare on Pound Street"), one allegedly cursed puppy ("Taboo", using the same voice she used for another Lucky), a sled dog ("Snow Problem") as well as the voice of other puppies in "The K9 Kid", "Call of the Squirreldog" and a number of other episodes.
Talking to Himself: The Pound Puppies' voice actors also provide the voices of their Kennel Kitten counterparts. Additionally, Alanna Ubach and John DiMaggio frequently voice pups, dogs, cats, and humans they cross paths with.
Eric McCormack voices both Lucky and Ace, which is appropriate, since the latter is basically a cat version of the former.