Nobody has been sick here for a long time, so I doubt that was an issue. The vet just thinks she either wasn't getting enough food in her or just wasn't digesting it. The other 4 have always eaten fine. I had a slight weight issue with Twitch when she was younger but she's been back up to a good weight for months. She is the most ferocious ferret I have. She doesn't let anyone take her food away. Lilly was always the timid one though. She would let herself get pushed away from the food or she would eat very very slowly so by the time everyone was full to bursting, she had only had a few bites. When I saw her start to lose the weight I intervened by hand feeding her ground food and fattier foods. (like the skin off chicken and things like that) and she was eating it just fine but I guess she wasn't keeping it down or maybe it passed right through her and I just didn't notice.