If you don't find feces in the litter box there can be a few reasons, and we will help you trouble shoot.
Before attributing this to a behavior reason, we must first consider medical reasons. The medical term for this condition is constipation. The number of defecations can vary, and normally a cat should have 2-4 bowel movements per 24 hours. If it has been more than 48 hours since the cat has defecated, the cat needs to be evaluated by your veterinarian.
NEVER use over-the-counter enema solutions designed for humans. Some of them contain substances that can be deadly to cats.
When you are using a non-clumping litter of any kind it can be sometimes difficult to verify how much the cat is actually eliminating. Dump the litter and use fine granulated clumping litter. This will make it easier to actually see the fecal clumps. Then clean the box regularly, removing the fecal balls each time the cat has eliminated. This allows you to assess how many actual bowel movements there are.
The cat may be defecating in places other than the litter box provided. Check your entire home to find fecal matter. Then check if the litter box is easily accessible for the cat. Refer to the Litter Box Problems and Litter Box Tips handouts for tips on trouble shooting eliminating outside the litter box problems.
This document created by the San Francisco SPCA with a grant from Maddie's Fund®