When a cat stops using the litter box

Few things test a cat owner like finding a puddle by the door, and the instinct to read it as revenge is exactly the wrong start.

Cats don't do spite. A cat that abandons its tray has a reason, and the reasons come in a rough order of urgency that's worth following in order.

The vet comes first, and sometimes today

A sudden change in toilet habits is a medical symptom until proven otherwise.

Cystitis, urinary crystals or stones, a urinary infection, arthritis that makes the tray hard to climb into, and the diseases that make a cat drink and urinate far more than usual — kidney disease, diabetes, an overactive thyroid — all send cats out of the box.

One version of this is an emergency. A cat straining in the tray with little or nothing coming out, going in and out repeatedly, crying, or licking at itself constantly may have a blocked urethra. That's most common in males, it's fatal within a day or two, and it needs a vet the same day rather than an appointment next week.

If you're reading this at eleven at night about a straining male cat, stop reading and phone the emergency line.

Spraying is a different behaviour from missing the tray

Worth separating early, because the causes and fixes differ.

Spraying is territorial marking: the cat stands, treads, quivers its upright tail, and leaves a small amount of urine on a vertical surface at nose height — a wall, a door frame, the side of the sofa. Inappropriate urination is a cat squatting and emptying its bladder on a horizontal surface, usually because something about the tray or its own body is wrong.

Puddles on the floor point at the tray, at stress, or at illness. Marks up a wall point at territory — a new cat in the house, a cat visible through the window, a move, an unneutered cat — and spraying has its own page, because almost nothing on this one will help with it.

Then the tray, from the cat's point of view

Cats are exacting about their toilet, and most protests are about the box rather than the cat. Run through it as a list.

Cleanliness. Scoop daily, wash the tray with unscented soap rather than anything strongly perfumed, and change litter completely often enough that it never smells. A tray that smells fine to you may already be unacceptable.

Number and placement. One tray per cat plus a spare, in separate quiet places rather than lined up in one room — two trays side by side count as one to a cat. Not next to a washing machine that starts unpredictably, not in a dead end where another cat can block the exit, and not beside the food.

Size and lid. A tray should be about one and a half times the cat's length, which is larger than most sold. Many cats dislike hoods, which trap smell and remove the ability to see out; if you have a covered tray, try it without the lid.

Litter. Depth of a few centimetres, and unscented — perfume is added for humans and repels plenty of cats. Most cats prefer a fine, sand-like clumping litter, and a cat that has recently gone off the tray after a brand change is telling you something clear.

Height of entry. The one that catches out older cats. Arthritis is common in cats over ten and rarely obvious, and a high-sided tray becomes painful to climb into long before anyone notices a limp. A low-entry tray, or a storage box with one side cut down, fixes an alarming number of cases in elderly cats.

Change one thing at a time, and give each change a week. Changing five things at once tells you only that something helped.

The cafeteria test

When you can't work out what the cat objects to, stop guessing and let it vote.

Put out several trays at once, side by side but a little apart, each set up differently: one with fine clumping litter, one with a coarser wood or paper litter, one filled deeper, one shallower, one with the lid off, one with lower sides. Then leave them a week and see which fills up.

It looks absurd in a small flat and it answers in days what otherwise takes months of one-change-at-a-time. Cats have strong and specific preferences about substrate, and most owners discover their cat's preference is not the one they'd been providing.

If the answer turns out to be soil, sand or the bath, that's information too: a cat choosing a smooth cool surface is often one with a sore bladder, which sends you back to the vet rather than to the pet shop.

Then stress and territory

Once health and housekeeping are ruled out, look at what has changed.

A new pet, a new baby, a move, building work, a new schedule, a cat outside the window, or tension with a housemate cat guarding the route to the tray — cats respond to change in the litter tray more visibly than anywhere else.

The fix is usually resources and predictability rather than reassurance: more trays in more places, hiding spots and high perches so a worried cat can get out of the way, feeding at consistent times, and separating the cats' resources so nobody has to queue. Introducing a new cat covers the version of this that comes with a second cat.

In a multi-cat home, watch who is actually using which tray before you conclude anything. Owners routinely blame the wrong cat, and a camera pointed at a tray for two nights settles it — often revealing that the cat everybody assumed was fine is the one waiting outside the door.

Cleaning up properly, because the spot invites a repeat

Use an enzymatic cleaner made for pet urine rather than a household one, and never one containing ammonia — ammonia is a component of urine, so an ammonia cleaner leaves a scent that says this is the toilet.

Blot rather than scrub, soak the area properly rather than wiping the surface, and check with your nose at floor level rather than standing up. A cheap ultraviolet torch shows you what you've missed, which is usually more than you thought and further from the obvious spot.

If a particular spot keeps being used, make it unattractive and the tray attractive at the same time: put a tray there temporarily and move it a few centimetres a day, or put food or a cat bed on the spot, since cats avoid soiling where they eat and sleep.

Carpet and underlay are the hard case. Urine soaks through to the backing and sometimes the floorboards, and cleaning the surface alone leaves a scent marker the cat can still read perfectly well. For a spot that keeps recurring, the underlay usually has to come up.

Never punish it

Shouting, rubbing a cat's nose in it, or shutting it in a room with the tray all teach the same lesson: the person is unpredictable, and it's safer to go somewhere the person isn't.

Punishment also raises stress, and stress is on the list of causes — so it can convert a housekeeping problem into a behavioural one.

There's no version of this where the cat understood and chose to defy you. A cat doesn't know your carpet is expensive, and it has no concept of a gesture aimed at you.

When to bring in help

See a vet first for any sudden change, any straining, any blood, any cat that's also drinking more, and any older cat that has started missing the tray.

Once medical causes are excluded and the tray has been made as inviting as it can be, a cat behaviourist is the next step, and referral through your vet is usually the reliable route.

Persistent house soiling is one of the most common reasons cats are given up, and it's also one of the most fixable — which is a good reason to work the list in order rather than to guess. For an older cat, what changes with age covers the other things that shift at the same time.