Do you have some kind of strange bedding in there that they are reacting to? I don't know a lot about rodents yet, but from what I have read there are some toxic woods that they shouldn't be around and I believe cedar is one of them. erodent.co.uk is a good guide to basic rodent care. Rats aren't in there but from what I have found so far most rodents are similar in certain ways.
Hopefully someone can correct me if I am wrong, but I would check that out to see if it is the problem!
Hopefully someone can correct me if I am wrong, but I would check that out to see if it is the problem!