Jump was the pet dog of the deceased Tobio. Jump later became part of Astro's family, despite not accepting Astro at first.
1980 Manga Series
In the 1980's series, jump plays an important role in accompanying Astro in many endeavors, even going into outer space with him. In the episode "Robot Vikings" Jump is critically damaged, and nearing the end, is expected to die. Luckily, after Astro saved Atlas's life, Atlas agreed to make a serum to cure the dog. Atlas dropped it off saying only "Inject him with this and he will be instantly cured. Tell Astro I've payed my debt." he dose not appeere in the 2003 series or the movie.