The first thing you should do is change the type of litter you use. Cats don't like sharp, rough edges on their feet, and sometimes even large cats will step on their waste when they dig around in their litter boxes. A smooth-edged litter may help solve this problem. If you're using clumping litter, try switching to non clumping, which tends to be less dusty and easier on sensitive paws. Depending on how big your cat is, you may also want to consider buying a larger litter box with higher sides than the one you currently have.