I'm having a problem with my 13 yo spayed cat. She quite suddenly started urinating outside her litter box. We had a covered box with little steps leading to actual litter and she would just wee on the steps (after using it correctly for several years!). We replaced that with a covered box with a swing door. She wouldn't go in at all so I took off the door. Then she'd go in to poop but not pee so i took off the lid. Now she poops in the box regularly. When she pees; however, she stands near the edge of the litter (but inside the box) with her fanny sticking out. Naturally the pee just goes on the floor. She isn't even bothering to try to cover any waste, solid or liquid with litter. I am keeping the litter pristine but nothing is working. Could she be senile?? Any suggestions would be appreciated.