When cats avoid the litter box, they are trying to tell you something. (tampabayvets.net)
Once your cat starts avoiding the litter box because it's painful to step in it, it can be difficult to return to normal. (kittycatter.com)
If your cat is still avoiding her litter box even after you've addressed behavioral issues, she may have a urinary tract infection or kidney disease, which is common in aging cats. (bluebuffalo.com)