While there is less of a chance of losing your hamster while he's in the exercise ball, you still need to always keep a close eye on him. (second-opinion-doc.com)
They increased in number for both winning and losing hamsters who had fought. (sciencenewsforstudents.org)
ive lost my hamster hes been missing for two days know and we have looked everywhere! (dwarfhamsterblog.com)