Why is my cat not using the litter box?

Finding pee or poo outside the litter box is frustrating, but your cat isn't being naughty or taking revenge. House soiling is one of the most common reasons cats end up in shelters, and it's almost always fixable once you find the cause.

Emergency first: a straining male cat

If your cat, especially a male cat, keeps going to the litter box and straining with little or no urine, crying in the box, or licking his genitals a lot, go to a vet immediately. This can be a urinary blockage, which is life-threatening within hours to days.

Step 1: rule out medical causes

A sudden change in toilet habits often has a medical cause. Common ones include:

• Urinary problems: cystitis (bladder inflammation, often stress-related), crystals, stones or infection. Signs: frequent small pees, straining, blood in the urine, peeing on cool surfaces like tiles or the bath.
• Arthritis: climbing into a high-sided box hurts (see arthritis in cats).
• Kidney disease, diabetes or an overactive thyroid: more pee, more often, sometimes more than the box can handle.
• Constipation or diarrhoea: a painful experience in the box can make a cat avoid it (see IBD in cats).

Book a vet check first, before changing everything at home.

Step 2: check the litter box setup

Cats are very particular about their toilets. Common problems:

• Not enough boxes. The rule of thumb is one box per cat, plus one. Three cats need four boxes, in different places.
• Not clean enough. Scoop at least once a day, and wash the box regularly with mild, unscented soap.
• Wrong litter. Most cats prefer fine, unscented, clumping litter. Scented litter and strong cleaning products can put them off.
• Too small or covered. Many cats prefer a large, open box, about 1.5 times the length of the cat.
• Bad location. Noisy places (next to the washing machine), busy corridors, or right next to food and water. Choose quiet, private spots with an escape route.
• High sides for older cats: offer at least one low entry.

Step 3: look for stress

Stress can cause both cystitis and house soiling. Common triggers: a new cat, baby or partner, moving house, building work, cats outside the window, or tension between cats at home. A cat might be "ambushed" at the litter box by another cat.

What helps: boxes in different areas so no cat can guard them, plenty of hiding and resting places, predictable routines and daily play.

Spraying is different

Spraying (a small amount of urine on vertical surfaces like walls or curtains) is scent marking, often linked to stress or other cats. It's most common in unneutered cats: neutering helps a lot. Cats that spray usually still use the box normally.

Cleaning up accidents

Use an enzymatic cleaner designed for pet urine. Ammonia-based cleaners smell like urine to cats and can attract them back to the same spot.

Never punish

Shouting, rubbing a cat's nose in it or punishing them makes things worse: it increases stress and can make the cat hide to pee. Be patient, find the cause, and fix it together with your vet.