Why is my cat weeing outside the litter tray?

House soiling is the most common behavioural complaint about cats and the most commonly misread. Cats are fastidious and do not do this out of spite or protest — the concept does not apply. They do it because something hurts, because the tray is unacceptable, or because they no longer feel safe getting to it. Separating urination from spraying matters too: squatting on a horizontal surface is elimination, while a small amount sprayed backwards onto a vertical surface with a quivering tail is marking, which is a different problem.

Safety

Step by step

1. Rule out the medical causes first, urgently.Cystitis, bladder stones, urinary blockage, kidney disease, diabetes, hyperthyroidism and arthritis all cause this. A male cat straining without producing urine is an emergency. Take a description of the frequency, volume and any straining or vocalising to the appointment.
2. Consider that arthritis makes trays hard to enter.An older cat that has started missing may simply be unable to climb a high-sided or hooded tray comfortably. A tray with one low side, or a baking tray, resolves a surprising number of these cases.
3. Count the trays.The established guidance is one tray per cat plus one spare, in different locations. Two cats need three trays, and two trays side by side count as one resource because a cat can guard both.
4. Check the size and type.A tray should be at least one and a half times the cat's length so it can turn and dig. Most sold are too small. Open trays are preferred by most cats; hoods and flaps suit owners. GuideHQ's guide on setting up a litter tray covers the specification.
5. Look at where they are.Quiet, with an escape route, not next to the food and water, not next to a noisy appliance, and not somewhere the cat has to pass another cat or a dog to reach. A tray in a utility room next to a washing machine is a common cause.
6. Review the litter.Cats form strong substrate preferences. Scented litter, a recent change of type, or a texture the cat dislikes will all cause avoidance. Change back if the problem started with a change, and offer two trays with different litters to let the cat choose.
7. Increase the cleaning.Scoop at least twice a day. A cat will not use a soiled tray and will find somewhere clean instead. Do not use strongly scented cleaners, and never use phenolic disinfectants — the ones that go milky in water — because they are toxic to cats.
8. Think about what changed.A new cat in the household or in the garden, a new baby, building work, a house move, a change in routine, a cat flap that lets a strange cat in. Stress-related cystitis is real and common, and the trigger is often visible in the previous fortnight.
9. Clean soiled areas with an enzymatic cleaner.Ordinary household cleaner leaves residue the cat can smell and returns to. Enzymatic pet cleaners break the compounds down. Never use anything ammonia-based — ammonia smells like urine and advertises the spot.
10. Make the soiled spot unattractive and the tray attractive.Once cleaned, block access, put food or a bed there, or place a tray on the spot temporarily and move it gradually. Meanwhile make sure there is an excellent tray available a short distance away.
11. Get a behaviour referral if it persists.Where medical causes are excluded and the resources are right, ask your vet for a referral to a clinical animal behaviourist. Insurance frequently covers this on referral.

Common mistakes

• Assuming it is behavioural before seeing a vet — Medical causes are extremely common, and in a male cat a urinary blockage is fatal within a day or two.
• Punishing or shouting — Stress is one of the causes. Punishment increases it and teaches the cat to avoid you rather than to use the tray.
• Cleaning with an ammonia-based product — It smells like urine to a cat and marks the spot as a toilet.

Questions people ask