So I'm trying to get my rat colony off the ground, and I'm doing ok. Built my own rack, which is will post pictures of one of these days. I've got several females that I'm trying to grow out to breeder size. Got a handful of older, bigger girls to breed sooner hopefully. Anyway, tonight I go into the snake room to check on all the snakes, and the rats, refill water, ect.. I notice right off that one rat is getting skinny and kinda sneezing. I pick her up and turn her over, and she is very lethargic. Since all my rats so far have come out of feeder bins, I'm trying to be picky about which one stick around, so she goes in a snake tub. So I go I checking the others, and i have another one in her box that is thin and slow also, not as bad, but breathing very heavily. I also had one in another box that was like that too, also fed off. Is this just respiratory problems? Should I switch from pine to aspen and see if it fixes it? Any suggestions?