* Not enough litter boxes
* Unclean litter boxes
* Unpleasant litter
* Litter box is too small
* Litter box is in a bad location
Medical issues
* Constipation
* Bowel obstruction
* Inflammatory Bowel Disease (IBD)
* Allergies
* Anal gland issues
* Diabetes
Behavioral issues
* Stress
* Anxiety
* Boredom
* Marking territory
In some cases, a cat may defecate next to the litter box simply because it has learned that this is an acceptable place to do so.
If your cat is consistently defecating next to the litter box, it's important to first rule out any medical conditions that may be causing the problem. Once medical causes have been ruled out, you can then focus on addressing any behavioral or environmental issues that may be contributing to the problem.