Lenny is a Golden Retriver, mother of Mel, who appeared only in the manga.

She was a former pet dog and had six puppies, all that found a home except for Mel, who stayed with her. Unfortunately, their house was too small for two dogs and soon, they were separated. Weed and GB found Lenny drinking nearby a river, clearly very ill. Weed decides to help her when she told the two that she's searching for her son. In their old house, Lenny finds another dog and later discovers that Mel is staying with Blue. The three dogs go to see Blue and find Mel, who attacks his mother, angered by the fact that they got separated, when she had promised that they would stay together forever. Lenny leaves but gets back to her son once she got to know from Hook that Blue is used to kill pups. Still, Mel doesn't want to go with her and tries to kill her, but can't. Blue then decides to do Mel's job and attacks Lenny. Mel is too weak to protect her and they are saved by Hook, who came to the rescue with a pack of dogs.

Lenny is reunited with her son but dies shortly after from her illness.

Lenny was supposed to appear in the anime. She is shown in one of anime character size charts.