Cats pee outside the litter box for several main reasons: medical issues, problems with the litter box itself, stress or anxiety, and marking behavior. Medical problems such as urinary tract infections, bladder inflammation, kidney disease, diabetes, arthritis, and feline idiopathic cystitis can cause discomfort or pain when urinating, leading cats to avoid the litter box or have difficulty reaching it in time.
Cats also dislike using a litter box that is dirty, has an unpleasant type of litter, or is in a location they find scary, hard to access, or dominated by other pets.
Stressful changes in the household like new pets, visitors, renovations, or changes in routine can make cats anxious and cause them to pee outside the box. This is not revenge but a stress response.
Finally, some cats mark territory by peeing outside the box, especially on vertical surfaces, if they feel stressed or threatened.
For persistent issues, it is advisable to consult a veterinarian to rule out medical causes and get advice on behavioral and environmental adjustments.
