We've got two ferrets who live roaming free in our living room, one is a healthy weight but the other is really chubby. When we first got him he was the runt of a family of rabbiting ferrets so he was severely underweight and malnourished. We've always free-fed our other ferret and he's never had weight issues, but Rolo just keeps piling on weight. We got him towards the start of the year but it's only been in the last couple of months that he's started to get really fat. We moved house about 2 months ago so not sure if this would have something to do with it, but he seems to have settled in okay and still likes playing with his brother. Is this sort of weight gain normal or should we be worried?