Cats poop outside the litter box primarily due to medical issues, stress, behavioral problems, or problems related to the litter box itself, such as cleanliness, size, location, or the type of litter used.

Medical Causes

Health problems like constipation, diarrhea, arthritis, inflammatory bowel disease, urinary tract infections, or cognitive dysfunction can prevent a cat from using the litter box properly. For example, pain or difficulty in reaching or using the box can cause them to relieve themselves elsewhere.

Litter Box Issues

Cats may avoid the litter box if it is dirty, too small, hard to access, or placed in an uncomfortable or high-traffic area. Cats also have preferences for certain litter textures and box types, and not meeting these can lead to outside pooping.

Stress and Behavioral Reasons

Changes in the cat's environment, like moving house, introduction of a new pet, new family members, or loud noises can cause stress and lead to litter box avoidance. Territorial marking through pooping outside the box is rare but possible, especially among unspayed or unneutered cats.

What to Do

If a cat starts pooping outside the litter box, it is crucial first to rule out medical problems with a veterinarian. Then check the litter box conditions and try to reduce stressors in the cat's environment. Multiple litter boxes in quiet, accessible locations are recommended, and cleaning the box frequently is important.

In summary, cats poop outside their litter box often due to illness, discomfort, dissatisfaction with the box, or stress, and resolving these issues usually corrects the behavior.