House-soiling, urinating or defecating outside the litter box, is one of the most common behaviour problems reported by cat owners and a frequent reason cats are given up or euthanased (Carney 2014). It has two very different forms, toileting outside the box and urine marking, and a long list of medical causes. The workup always starts with a medical evaluation, then works out which form is present, because the treatments differ.
Key facts
Housesoiling at a glance- Species and system: cat; behaviour, with urinary and gastrointestinal overlap.
- Four basic causes: medical disease, feline idiopathic cystitis, urine marking, and elimination problems driven by the physical or social environment (Carney 2014).
- Marking: small amounts of urine on vertical surfaces, standing posture with the tail up and twitching; the litter box is still used (Merck 2025).
- Toileting: full voids on horizontal surfaces in a squatting posture, often from a litter box aversion or preference.
- Persistent marking after neutering: about 10% of neutered males and 4% of neutered females (Carney 2014).
- Not zoonotic and not reportable.
What's inside
12 sections in the full guide- Key facts
- How the NAVLE tests this
- Cause and pathophysiology
- Clinical signs
- Diagnosis
- Differential diagnoses
- Treatment and management
- Prevention
- Prognosis
- Quick review
- Test yourself
- References
The full guide also has 5 tables, 2 figures, 3 self-test questions and 10 references, available to NAVLE members.
Read the full study guide
The full guide is part of every NAVLE plan, with diagnosis and treatment tables, figures, a quick review and self-test questions. Start a free trial to try the question bank, or log in if you are already a member.