my rat mochi

Question
recently my rat has started draging his back legs around. He still very playful and doesn't seem to be in pain. He's about 4 yrs old.besides having to bathe him and clean his cage more often, all is well. The only thing different i can see is that when I get him wet his skin is got dark grey splotches now.(hes white so ist noticable)I just dont want him to be put to sleep.

Answer
This can happen with old age. It could be a compressed nerve or spinal injury, arthritis, or even a tumor on the spinal cord. Either way, he's an old guy, so you just have to make him as comfy as possible. Lower ramps and pad the floor bottom with soft material so he doesn't give himself sores. Make sure you make his cage as handicap-accessible as possible!