My 12 (going on 13)-year-old Lionhead seems to have developed a sore on one of his back hind feet. He's never been a particularly active rabbit (he has the run of the house but prefers to stay in his cage), but he's never had any problems like this before. He does have a wire mesh cage, with half the cage covered in blankets and towels and half the cage for his food dish and peeing area. Again, he's never had a problem with this set up, in the 10 years I've had him. Sometimes he even prefers to sleep and rest on the wire mesh. The sore is about the size of a pea and clean, not open or bleeding or anything. It looks like the fur has been chaffed away and the skin is red and inflamed underneath, but he doesn't seem to be in any pain because of it (no grinding his teeth, didn't flinch when I gently prodded at it). Curious if there's anything I should be doing. If it's a mobility issue because of his age, should I be adding more padding to his cage? Should I be treating the sore with anything or should I just keep an eye on it? Any help would be appreciated. Thank you.