I am watching a pair of rats for the next few months. This afternoon, I went to check on them and one is having a serious issue with his back legs/hindquarters. He can move his legs slightly, but cannot seem to use them for support--and he is walking by dragging himself. As far as I can tell--he is not in pain, and he is eating/drinking/defecating properly. He is about 8 months old. It seems too young for a stroke or cancer, and I haven't observed any evidence of trauma (except for a bit scuffling between him and his cage-mate). It was very sudden, also--this morning he seemed fine, but by the afternoon he was in trouble. I have put him in a separate, single-level enclosure, and he is going in to the vet tomorrow, but it seems strange. Has anyone else had this experience?