Why Is My Cat Pooping Outside the Litter Box? 8 Causes, and How to Tell Which One Is Yours

A cat that has used its box reliably for years and then starts leaving stools next to it, behind the sofa or on the landing has not become spiteful and has not forgotten its training. Something has changed, and the change is usually either inside the cat or inside the box.

This guide is organised so you can narrow it down rather than work through a list of eight things to try at random. There are two questions up front that eliminate most of the possibilities in a day, then the eight causes with the sign that identifies each one, then what to do and in what order.

Before anything else: the two questions that sort this fastest

How long has it been happening? Something that started in the last few days, in a cat that was previously reliable, points at the cat rather than the furniture. Cornell's Feline Health Center puts the veterinary visit before the detective work, and gives the reason people underestimate: "Once you have identified the house-soiling cat, it is wise to take him to your veterinarian for a thorough physical examination and appropriate diagnostic tests to check for underlying medical problems. Cats with medical conditions may not always act sick."

The AAFP and ISFM house-soiling guidelines make the examination specific, and the detail that matters here is what they include in it: "Perform a thorough physical examination (including a basic orthopedic and neurologic assessment) on every house-soiling cat". Orthopedic, because a cat that cannot comfortably climb into a box or get down a flight of stairs will find somewhere closer, and nothing about that cat looks ill.

Does it still urinate in the box? This is the question almost nobody asks, and it eliminates more than the first one. A cat that pees in the box and poops beside it is not rejecting the box, the litter, the location or the cleanliness, because it is using all of them several times a day. That single observation removes about half of the standard advice, and it has its own section below.

Only after those two does the order of causes below make sense. The first four are medical, and they come first because that is the order every veterinary source uses. Cornell's phrasing marks the handover: "Once medical causes have been ruled out, your detective work begins."

Cause 1: constipation

Constipation is the cause most often named and least often explained. Cornell's definition is worth having in your head because it is more specific than "not going much": "Constipation, defined as infrequent or difficult emission of hard, dry fecal matter, is a common problem of the domestic cat." The same page adds a reason not to wait and watch: "It is important to treat it fairly aggressively to prevent progression."

The sign that identifies it. Repeated trips to the box that produce nothing or produce small hard pellets, longer sits, and sometimes a stool deposited a step or two away from the box after a long effort inside it. Straining in the box is easy to mistake for a urinary problem, and in a male cat that distinction is an emergency rather than an inconvenience, so it is one to settle with a vet rather than from a web page.

Who it happens to. The MSD Veterinary Manual names the risk profile: "Older, overweight cats (with poor colonic muscle contraction), cats with chronic kidney disease (that are chronically dehydrated), and those with previous episodes of constipation are at increased risk of constipation." An older cat, a heavy cat or a cat with kidney disease that starts leaving stools around the house is in the group where this is checked first.

There is also a loop worth knowing about, because it explains cases that look purely behavioural. A cat that avoids a box it dislikes holds on, holding on makes the stool drier and harder, and the harder stool makes the next attempt unpleasant. By the time you notice, the box problem and the medical problem are feeding each other and fixing one alone does not settle it.

Cause 2: diarrhoea and urgency

The opposite problem produces the same symptom by a different route, and the guidelines pair them deliberately in the fecal workup: "The clinician should also determine whether the cat has chronic or acute constipation or diarrhea."

Cornell explains the mechanism in a sentence that covers urgency, frequency and control at once: "Similarly, digestive tract problems may make it painful for a cat to defecate, increase the frequency or urgency, and decrease a cat's control over defecation."

The sign that identifies it. Soft or liquid stools, more of them than usual, and accidents that happen on the way to the box rather than somewhere the cat has chosen. A cat with urgency does not select a spot; it runs out of time. Stools found in the middle of a route, part-way between where the cat was and where the box is, fit this and almost nothing else.

This is also the group where intestinal parasites and inflammatory bowel disease sit. They are part of what the vet is looking for with a faecal sample and a work-up, and they are not things you can rule in or out at home.

Cause 3: pain, and the box that becomes the place it hurts

This is the cause that turns a short medical episode into a long behavioural one, and it is why "we treated it and the behaviour continued" is so common.

Cornell states the general rule and then the trap inside it: "Any medical condition that interferes with a cat's normal urination or defecation behavior can cause litter box problems." and the mechanism that outlives the illness: "These experiences can cause a cat to urinate or defecate outside the litter box, particularly if he associates the litter box with pain."

The sign that identifies it. The behaviour started at the same time as, or just after, an illness, and it did not stop when the illness did. The cat may approach the box, hesitate at the edge, and go elsewhere. Cornell describes the cluster to watch for at the box: "When your cat uses the box, does he cry, refuse to bury his waste, perch on the edge of the box without touching the litter, or eliminate right near the box?"

What breaks the association is a box that is not the box the cat learned to dread: a different shape, in a different room, with a different litter, offered alongside the existing one rather than instead of it. The cat gets to choose, and its choice tells you whether you were right.

Cause 4: arthritis and age, when the cat cannot get in or cannot get there

This one is badly under-diagnosed by owners because the cat looks fine. It walks, it jumps less than it used to, and you file that under getting older.

The guidelines are direct about what stiff joints do to box access: "inflexible joints may limit a cat's ability to access its litter box", and they give the specific adaptation: "For example, cats with degenerative joint disease may require a litter box with a very shallow opening".

Distance is the other half, and it is the part people do not think of as an access problem: "Debilitating conditions such as arthritis, muscle weakness and impaired vision can impede the ability of elderly cats to reach litter boxes that are located in basements or far from the cat's core territory." Cornell says the same thing about the specific obstacle in most homes: "Cats with painful arthritis may have difficulty gaining access to a litter box, especially if negotiating stairs is required."

And there is a third version of the same problem that is not about joints at all: "age-related diseases that interfere with a cat's mobility or with his cognitive functions can influence his ability to get to the litter box in time".

The sign that identifies it. The cat is over about ten, the accidents are close to where the cat sleeps or on the floor the cat spends its day on, and the box is either high-sided or on another level. A useful test costs nothing: put a low-sided box, or a tray with one side cut down, on the floor the cat actually lives on, and leave the old one where it is. If the new one gets used within a few days, you have your answer and you did not need a diagnosis to get it.

Cause 5: the box itself is too small, too dirty, or the wrong litter

Now the box, and the three variables that do most of the work.

Size. None of the pages that currently rank for this question give a measurement, and the guidelines do: "We recommend a rectangular litter box that is 1.5 times the length of the cat from nose to base of tail; in one study, adult cats preferred a box that was 34 x 15 inches (86 x 39 cm) over a smaller one". Most boxes sold as large are smaller than that, and a cat that cannot turn around comfortably will often urinate in the box and step out to defecate, because defecating takes longer and needs more room.

Cleanliness. This is where the strongest evidence sits. A 2023 survey of Italian households found that "scooping frequencies lower than once a day significantly increased the odds of house-soiling". Ohio State states the consequence in plain language: "Most cats will avoid using a dirty litter box in favor of a cleaner place." And Cornell gives the limit case, which explains the cat whose box looks fine to you: "Some cats refuse to use a box containing any urine or feces whatsoever."

Litter, and the depth question where the sources genuinely disagree. On type there is no argument. Cornell: "Most cats prefer unscented, finer-textured litter about one to two inches deep." The guidelines agree and add what to leave out: "In most cases, the litter should consist of a fine, sand-like, non-scented, clumping material to a depth of at least 1.25 inches (3 cm). Avoid liners, slotted grills or deodorizing powders." The ASPCA is more specific about the accessories: "Most cats don't like box liners or lids on their boxes."

On depth the published advice is not consistent, and it is worth saying so rather than picking whichever number suits. The ASPCA says "Cats usually prefer one to two inches of litter.", Ohio State asks for "enough litter to permit the cat to scratch and bury waste (usually about 2 inches deep)", and the guidelines set a floor rather than a target at 1.25 inches. Litter brands often recommend three to four. The range that every veterinary source agrees on is roughly one to two inches, so start there, and treat deeper filling as something to test rather than assume.

The sign that identifies this group. The cat goes right next to the box rather than in another room. Proximity is the tell: a cat that objects to the contents of the box still wants to go where the box is, so it goes as close as it can stand.

Cause 6: the box is in the wrong place

Placement causes the same symptom as a rejected box, but the stools appear where the cat feels safe rather than beside the box.

Cornell's criteria are the shortlist: "Most cats prefer a location that is quiet, private, separate from their feeding area, and easily accessible 24 hours a day." Ohio State adds the startle problem, which is the one owners never suspect because it happened once and they were not there: "Litter boxes should be placed away from appliances or air ducts that could suddenly come on and startle the cat." And the route counts as much as the room: "Consider the path the cat will take to reach the litter box."

One placement finding is specific enough to act on tonight. The 2023 Italian survey reported that "placing litter boxes near or under stairs seemed to increase the likelihood of house-soiling, most probably because stairs are a noisy place where many people, sometimes strangers, pass by". The understairs cupboard is one of the most popular places to hide a litter box and one of the worst available.

The sign that identifies it. The cat chooses one consistent alternative spot, and that spot is quiet, has a clear view and more than one exit. The cat has not stopped being tidy, it has picked a better location than yours by its own criteria. Where it has chosen tells you what the box's location is missing.

Cause 7: it urinates in the box and defecates outside it

This is the most informative pattern there is, and none of the pages currently ranking for this question has a section for it.

Start from what it rules out. A cat that urinates in the box several times a day accepts the box, the litter, the depth, the location and the level of cleanliness, at least for urinating. So the explanation cannot be a general aversion to any of those, which removes most of the standard checklist in one step.

What remains is either something that makes defecating specifically uncomfortable, which is causes one to four above, or this, which the guidelines state directly: "Most cats prefer private places to eliminate rather than busy locations, and may need different locations for urinating and defecating."

Defecating leaves a cat exposed for longer than urinating does. A location that is just private enough for a quick visit can be not quite private enough for a long one, and the cat resolves that by splitting the two functions between two places. If the second place it has chosen is your rug, the fix is to give it a second box somewhere quieter rather than to keep improving the first one.

What to do with this one. Add a box in a quieter, lower-traffic spot than the existing box, on the same floor the cat spends its day on, and leave the first box exactly as it is. If the new box takes the stools within a week or two, the answer was two locations rather than one better location. Deciding where the second box goes, and why two boxes in the same room do not count as two, is set out in our guide to how many litter boxes per cat you need and where to put them.

Cause 8: another cat, and when it is middening rather than toileting

In a multi-cat house there are two different things going on, and telling them apart changes what you do.

The first is access. The guidelines name the pattern: "In a multi-cat household, overcrowding or the presence of a 'despot' cat that monopolizes litter box resources may cause less confident cats to seek out inappropriate places for elimination." It rarely looks like aggression. It looks like one cat sitting on the landing, and another cat quietly no longer going upstairs. Ohio State describes the same dynamic from the box's point of view: cats may avoid a box "when they are afraid to use the box because it is placed such that a quick escape from another cat would not be possible", and its remedy is separation of resources: "providing a separate set of resources for each cat, preferably in locations where the cats can use them without being seen by other cats".

The second is communication, and it has a name most owners have never heard. Christine Calder, a veterinary behaviourist, separates the two categories: "Urination or defecation (pooping) outside the litter box falls into two categories: toileting and marking." and defines the second: "Marking, or middening, occurs when a cat uses feces instead of urine to make a statement or communicate."

How to tell them apart in ten seconds. Toileting looks like going to the toilet: somewhere tucked away, often close to the box, and the cat makes some attempt to cover. Middening looks like a message: left uncovered, in the open, on a route or a boundary such as a doorway, the top of the stairs, a bed, or next to a door to the outside. A stool placed conspicuously where the household walks is behaving like a signal, and adding a box is not the answer to a signal. What is, is reducing whatever the cat is signalling about, which is usually another cat, indoors or outside the window.

The guidelines put the same fork in clinical terms, and it is the reason the veterinary work comes first: "As with house-soiling involving urination, if all diagnostic values are within normal limits, aberrant marking behavior or elimination related to primary environmental or social factors are the most likely causes of house-soiling with stool."

How to tell which one is yours

One row per cause, with the observation that points at it. Read down the middle column and look for the one that matches what you have been seeing.

Cause	What you would be seeing	First move
Constipation	Repeated trips producing little or nothing, hard dry pellets, long sits, a stool dropped a step from the box after a long effort	Vet, and soon. Straining is also how a urinary blockage looks, which is an emergency
Diarrhoea and urgency	Soft or liquid stools, more often than usual, accidents part-way along the route to the box	Vet, with a faecal sample
Pain, and the association that outlives it	Began with an illness and did not stop when it resolved; hesitating at the edge, crying, perching, not burying	Vet first, then offer a different box in a different room alongside the old one
Arthritis or age	Cat over about ten, accidents near where it sleeps or on its floor, box high-sided or on another level	Low-sided box on the floor the cat lives on, plus a vet check for joint pain
Box too small, too dirty, wrong litter	Stools right next to the box rather than elsewhere; box smaller than 1.5 times the cat; scooped less than daily; scented litter or a liner	Scoop twice a day for a fortnight before changing anything else
Wrong location	One consistent alternative spot that is quiet, open-view and has two exits; box near an appliance, a thoroughfare or the stairs	Put a box where the cat has been going, then move it gradually if you need it elsewhere
Needs a separate site for stools	Urinates in the box normally, defecates outside it	Add a second box somewhere quieter and leave the first one alone
Another cat, or middening	Multi-cat house, or stools left uncovered and conspicuous on doorways, beds, stairs or near an outside door	Separate resources per social group; for middening, work on the conflict rather than the box

What to do, in what order, and how long to give it

The reason people go round in circles here is that they change three things in one weekend and cannot tell which one worked, or whether any of them did.

First, the vet. Not because it is probably medical in your particular cat, but because the four medical causes are the ones that get worse while you experiment, and because the examination includes the orthopedic assessment that finds the cause nobody suspects.

Second, scooping. Twice a day for two weeks, before you buy anything. It is free, it is the change with the most evidence behind it, and it is also the control: if the behaviour stops, you have your answer and you have spent nothing.

Third, one change at a time, two weeks each. In this order, because it goes from most likely to least: add a box in a quieter place, then lower the sides or increase the size, then change the litter, then move the original box. A fortnight is the minimum useful window, since a cat that ignores a new object for a week is behaving normally rather than rejecting it.

And never as a step: punishment. Ohio State is unusually blunt about this, and lists the specific things owners do: "Don't scream at them. Don't rub its nose in it. Don't throw them into the litter box. This will make them more nervous, more upset, and more afraid of the litter box." Every one of those makes the box a worse place to be, which is the opposite of the objective.

Cleaning the spot, which decides whether it happens there again

Cleaning is not housekeeping here, it is part of the treatment, because the spot advertises itself. Cornell states the mechanism and the standard: "Cats will re-soil and spray areas they have marked with their scent, so cleaning cat-soiled items is crucial for breaking the cycle of elimination. Cleaning is most effective when it's done soon after an item was soiled, and odors must be neutralized, not just deodorized, to escape a cat's keen sense of smell."

The ASPCA names the product category that does the neutralising: "Clean accidents thoroughly with an enzymatic cleanser designed to neutralize pet odors."

And there is one thing not to reach for, which sits under most kitchen sinks: "Avoid cleaning products containing ammonia or vinegar as they smell like urine and can be irritating." Cleaning a spot with ammonia is closer to signing it than to erasing it.

If it is urine rather than stools

Urine outside the box is a related but separate problem, and one distinction does most of the sorting. Cornell describes what marking looks like, and the posture is the tell: "Cats usually spray on vertical surfaces, like the backs of chairs or walls. A spraying cat will stand, lift its tail and quiver, then spray small puddles of urine in several consistent locations", and the contrast that follows: "Cats don't squat to spray, as they do to urinate."

A cat that squats and leaves a full puddle on a horizontal surface is toileting, and everything in this guide about boxes, litter, cleanliness and location applies. A cat that stands and sprays a wall is communicating, and the work is on what it is communicating about. Either way, the veterinary check comes first, and for a male cat straining without producing urine it comes immediately.

What we sell, and what we do not

To be clear about who wrote this: Ziveko sells interactive and automatic cat toys, and at the time of writing we do not sell litter, litter boxes, enclosures, cleaners or anything else named above. That is worth saying on this page in particular, because this is a question a lot of shops answer with a product. The two steps that come first here, a veterinary examination and scooping twice a day, are the two we have nothing to sell you for.

The part we do know something about is the cat's day rather than its box. Social tension between cats in a household is more manageable when the cats have enough to do and enough separate space, which is the ground covered in signs your cat is understimulated. If the smell in the room is a problem of its own once the accidents stop, that is dealt with in how to make a litter box not smell, and if more litter is ending up on the floor after you change the box or the litter, how to stop cat litter tracking covers the trade-offs.

Frequently Asked Questions

Why is my cat pooping outside the litter box?

Most often for a medical reason, a box the cat finds unacceptable, or a need for a second, quieter place to defecate. Cornell advises taking a house-soiling cat to a veterinarian for a physical examination and diagnostic tests first, and notes that cats with medical conditions may not always act sick. The AAFP and ISFM guidelines add that the examination should include a basic orthopedic assessment, because stiff joints can stop a cat getting into a box. Constipation, diarrhoea, pain on defecating and arthritis account for the cases that no change to the box will fix.

Why does my cat pee in the litter box but poop on the floor?

Because the box is not being rejected. A cat that urinates in the box accepts its litter, depth, location and cleanliness, so a general aversion cannot be the explanation. Two possibilities remain: something makes defecating specifically uncomfortable, which is medical, or the cat needs a second site. The AAFP and ISFM guidelines state that most cats prefer private places to eliminate and may need different locations for urinating and defecating, since defecating leaves a cat exposed for longer. Adding a box in a quieter spot, while leaving the first one alone, tests that directly.

Is my cat pooping outside the litter box out of spite?

No. The behaviour is either toileting or marking, and neither is retaliation. Veterinary behaviourist Christine Calder separates them: urination or defecation outside the litter box falls into toileting and marking, and marking, or middening, occurs when a cat uses feces instead of urine to make a statement or communicate. Toileting is tucked away and often near the box; middening is left uncovered and conspicuous, on a doorway, a bed or a route through the house. Punishment makes both worse. Ohio State's advice is not to scream at the cat, rub its nose in it or throw it into the litter box, because that makes the cat more afraid of the box.

When should I take my cat to the vet for pooping outside the litter box?

Before you change anything else, and immediately if the cat is straining without producing anything, if there is blood, if the stools are liquid or if the cat has stopped eating. Cornell's guidance is to have a house-soiling cat examined for underlying medical problems first, because cats with medical conditions may not always act sick, and its sequence is explicit: once medical causes have been ruled out, your detective work begins. The MSD Veterinary Manual notes that older cats, overweight cats, cats with chronic kidney disease and cats with previous episodes are at increased risk of constipation.

How do I stop my cat pooping outside the litter box?

Rule out the medical causes, then change one thing at a time and give each change a fortnight. Start with scooping twice a day, which costs nothing and has the strongest evidence behind it: a 2023 survey found that scooping less than once a day significantly increased the odds of house-soiling. Then add a box in a quieter place, then lower the sides or increase the size, then try a different litter offered alongside the old one rather than as a swap. Clean every soiled spot with an enzymatic cleaner, and avoid ammonia and vinegar, which Cornell warns smell like urine to a cat.

Why does my cat poop right next to the litter box?

Proximity is the clue: a cat that goes beside the box still wants to go where the box is, so it is objecting to the box rather than to the place. The usual reasons are that the box is too dirty, too small or has litter the cat dislikes. Cornell notes that some cats refuse to use a box containing any urine or feces whatsoever, and the AAFP and ISFM guidelines recommend a rectangular box one and a half times the length of the cat from nose to base of tail, which is larger than most boxes sold. A cat that cannot turn around comfortably will often urinate in the box and step out to defecate, since defecating takes longer and needs more room.