Why Is My Cat Pooping Outside the Litter Box? Causes and Fixes

A cat that poops outside the litter box is nearly always telling you something is wrong with its body or with its toilet. The most common reasons are constipation, diarrhoea or pain (arthritis in older cats especially), a tray that is too small, too dirty or in the wrong place, too few trays for the number of cats, and stress. Cats do not do it out of spite. Start with a vet check if the change is sudden, then work through the tray set-up below. Most cats go back to the box once the cause is fixed.

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When to see the vet (and when it is urgent)

Cornell Feline Health Center calls house soiling the most common behaviour problem cat owners report, and says every house-soiling cat should have a full check, because cats with a medical problem do not always look ill. A sudden change in toilet habits is reason enough to phone your vet.

Call your vet straight away if your cat

• Strains in the tray and produces little or nothing. Straining to pee and straining to poo look almost the same. A blocked bladder is an emergency, and male cats are most at risk. If you are not sure which it is, treat it as urgent.
• Cries out or seems in pain when trying to go.
• Has diarrhoea together with vomiting, lethargy, blood or mucus in the poo, or a sore belly.
• Stops eating, or seems weak or unwell.

Book an appointment soon if

• Diarrhoea lasts longer than 24 hours, even if your cat seems fine otherwise (PDSA advice).
• The poo is small, hard and dry, your cat goes less often, or keeps going in and out of the tray.
• Your cat is older and seems stiff, sleeps more, jumps less or struggles with stairs or the cat flap.
• Accidents keep happening, even if your cat looks healthy.

Medical reasons your cat poops outside the litter box

Constipation

A constipated cat strains for a long time, passes small, dry, hard stools, may cry out, and spends a lot of time digging in the tray. If going hurts, your cat can start to link the tray with that pain and try somewhere else. International Cat Care names dehydration and pain (including arthritis) among the causes. PDSA advises contacting your vet whenever you see signs of constipation. Wet food and easy access to water help many cats stay regular, but let your vet find the cause first.

It works the other way round too. A cat that dislikes its tray may hold on for as long as it can, and that can lead to constipation.

Diarrhoea and soft stools

With diarrhoea, a cat often simply does not reach the tray in time. Sudden urgency also means poo just over the edge of the tray or on the floor next to it. A single loose stool in an otherwise bright cat can usually wait a day. PDSA advises calling the vet if it lasts longer than 24 hours or comes with other symptoms. Parasites, a food change, food intolerance and inflammatory bowel disease are all possible causes. If your vet suspects food, our guide to cat food for sensitive stomachs explains what to look for.

Arthritis and pain in older cats

This is the cause owners miss most often. According to PDSA, one study found signs of arthritis on X-ray in 90% of cats over 12 years old. Cats hide pain well, so you rarely see limping. What you do see is a cat that no longer jumps, uses the stairs less, and finds it hard to step over a high tray edge or to squat in the tray. The result is poo just in front of the tray, or on a rug nearby.

Help comes from both sides. Your vet can treat the pain, and you can make the toilet easier: a large tray with a low entry, a tray on every floor, soft fine litter instead of hard wood pellets (International Cat Care warns pellets can hurt sore paws). PDSA suggests a check every 6 to 12 months for older cats.

Senility (cognitive dysfunction)

Cornell lists cognitive decline among the reasons older cats stop reaching the tray. A senior cat may seem confused, wander at night or forget where the tray is. Extra trays close to where your cat sleeps help, and so does keeping the layout of your home the same.

Other medical causes

Urinary problems, kidney disease, an overactive thyroid and diabetes are better known for peeing outside the tray, but they make a cat feel unwell and can upset its whole toilet routine. That is another reason the vet comes first.

Litter box causes: the most common fixable reasons

Once your vet has ruled out a medical cause, look at the tray with your cat's eyes. Cornell puts it simply: the problem is usually the box, the litter, the location, or all three.

The tray is too small

Most trays sold as "large" are smaller than cats need. International Cat Care advises a tray about one and a half times the length of your cat (nose to base of the tail), so it can turn round and squat without its bottom hanging over the edge. A cat that perches on the rim and misses is a typical sign of a tray that is too small. Cat behaviourist Vicky Halls, writing for Cats Protection, treats a jumbo tray of about 49 by 38 cm as the minimum and suggests a large clear plastic storage box for big cats. Bigger cats, such as Maine Coons, often need the storage box route.

What owners say: reviewers keep mentioning that the high sides finally stopped a cat from peeing or pooping over the edge, often an elderly or large cat that used to sit too high in a standard tray. Several say their cat switched to it without fuss. The complaints are practical: it takes quite a lot of litter to fill, the rim is stiff to unclip at first, one owner in a hard water area found limescale at the bottom after long use, and a German reviewer would prefer a less slippery floor for older cats.

Too few trays

Cornell, International Cat Care and PDSA all use the same rule: one tray per cat, plus one extra. One cat needs two trays, two cats need three. Put them in different places, not side by side, so one cat cannot guard them all. This also applies to cats that go outdoors, because bad weather, a neighbour's cat or a dog in the garden can make the outdoor toilet feel unsafe.

The tray is in the wrong place

Cats want to feel safe when they are at their most vulnerable. A good spot is quiet and private, with a view of the room and a way out. Avoid:

• next to food and water bowls,
• busy hallways, or next to a washing machine or boiler that switches on suddenly,
• right by a cat flap, outside door or full-length window, where other cats can be seen or smelled,
• upstairs or in the basement for a cat that struggles with stairs.

Need to move the tray? Cornell suggests putting it where your cat already prefers to go, and once it is used reliably, moving it a few centimetres a day towards where you want it.

The tray is not clean enough

Many cats refuse a tray with poo already in it. International Cat Care advises removing poo and clumps at least twice a day, topping up with fresh litter, and emptying and washing the whole tray at least once a week with hot water and a mild detergent. Avoid strongly scented cleaners and any disinfectant that turns cloudy in water, as these usually contain phenols, which are toxic to cats. An old, scratched plastic tray holds smells, so replace it when it starts to smell even after washing. Our complete guide to cleaning the litter box has the full routine.

If you are out at work all day and cannot scoop twice daily, a self-cleaning box can help some cats, provided your cat is not nervous of noise and the box is big enough. Our comparison of the best automatic litter boxes explains which suit which cats. For a cat that is already avoiding its tray, fix the cause first, because a new machine is one more change.

The wrong litter, or too little of it

Most cats prefer fine, sand-like, unscented litter, according to both Cornell and International Cat Care. Scented litter and deodorising sprays smell pleasant to us and strong to a cat. Use at least 3 cm of litter. Some cats like it deeper to bury their poo, while very deep litter can feel unstable underfoot. Plastic liners are disliked by many cats because their claws catch on them.

Changed brands recently? That alone can explain it. Switch back, or mix the new litter in gradually over about a week, or put a second tray with the new litter next to the old one and let your cat choose. Kittens need extra care with litter type, see our guide to the best cat litter for kittens.

Covered or open

Cornell's advice leans towards open trays: a lid traps smells inside, and a cat cannot see who is coming. Some cats do like the privacy of a hood. If your cat poops outside a covered tray, the simplest test is to take the lid off for a couple of weeks.

Stress and changes at home

Cats are creatures of routine. A house move, a new partner, baby or pet, guests, building work, rearranged furniture, a change in your working hours or a strange cat in the garden can all unsettle the toilet routine. International Cat Care also mentions bad associations: a cat that was given a tablet, grabbed or startled while in the tray may avoid it afterwards. Fireworks and storms can do the same.

What helps: keep feeding and play at fixed times, give your cat high places and hiding spots, block the view of an outdoor cat that stares through the glass, and never use the tray as the place to catch your cat for a vet trip. Cornell mentions synthetic pheromone products such as Feliway, mainly for urine spraying. If accidents continue despite all this, ask your vet about a referral to a qualified behaviourist.

Multi-cat homes: is one cat guarding the tray?

In a multi-cat household, poo outside the box is often a sign of tension you do not see. One cat may sit near the tray, stare, or ambush the other on the way out. The timid cat then chooses a safer spot.

• Find out who it is. Cornell suggests a camera, temporarily separating the cats, or asking your vet about safe markers.
• Spread the trays. One per cat plus one, in different rooms and on different floors, so nobody has to walk past a rival.
• Choose open trays with an escape route. A hooded tray in a corner is a trap for a cat that is being bullied.
• Double up on everything. Food bowls, water, beds and scratching posts in several places reduce competition.

When cats really do not get on, a slow reintroduction often helps. Our guide on how to introduce cats explains the steps.

Pees in the box but poops outside it?

This is a common variant, and it narrows things down. A cat that still pees in the tray is not avoiding the tray completely, so look first at what makes pooing hard: constipation, pain when squatting (arthritis), a tray too small to squat in comfortably, or litter too shallow to bury in. An extra tray, so your cat always has a clean one to choose from, is an easy thing to try.

If your cat is peeing outside the tray as well, or instead, the causes overlap but the cleaning is harder. Read our guide on how to get rid of cat pee smell, and keep in mind that a cat straining to pee needs the vet the same day.

How to clean the spot so your cat does not come back

A cat smells what you cannot. If the scent stays, the spot keeps saying "toilet". International Cat Care's method:

1. Pick up the poo with kitchen paper and remove as much as you can. Do not rub it in.
2. Clean with an enzyme cleaner made for pet urine and faeces. These break down the organic matter that causes the smell. Our guide to the best enzyme cleaners for cat urine covers which ones work and how to use them.
3. No enzyme cleaner at hand? A 10% solution of biological washing powder, rinsed with cold water and dried well, is the alternative International Cat Care gives.
4. Optionally, once dry, mist lightly with surgical spirit and let it evaporate. Test on a hidden patch first, especially on delicate fabrics.
5. Avoid ammonia-based cleaners and vinegar. Cornell notes they smell like urine to a cat and can draw it back.

Then make the spot less attractive as a toilet. Cornell suggests putting food bowls or treats there, playing there, covering it with furniture or a plant, or shutting the door for a while. Some owners put a tray on the spot temporarily and move it gradually back once the cat uses it.

Step by step: how to stop your cat pooping outside the litter box

1. See your vet, especially if the change is sudden, your cat is older, or the poo looks abnormal. Note when and where the accidents happen and what the poo looks like.
2. Clean every spot with an enzyme cleaner, so old smells do not keep the habit going.
3. Count your trays: one per cat plus one extra, in different places.
4. Check the size: about one and a half times your cat's length. Upgrade to a jumbo tray or storage box if needed.
5. Lower the entry for kittens and older or stiff cats.
6. Check the location: quiet, away from food, not by the cat flap or an outside door, easy to reach day and night.
7. Simplify the litter: fine, unscented, at least 3 cm deep. Change brands gradually.
8. Scoop at least once and ideally twice a day, and wash the tray weekly with mild detergent.
9. Try without the lid if you use a hooded tray.
10. Find and reduce stress, and watch whether one cat is blocking another.
11. Be patient and calm. Never shout, hit or rub your cat's nose in it. Cornell and International Cat Care both say punishment makes cats more anxious and the problem worse. Your cat does not link the punishment to the mess.
12. Still no improvement after a few weeks? Go back to your vet and ask about a behaviourist.

Frequently asked questions