Cat not using the litter tray: causes and what to do

First things first: a cat never does this out of spite. Revenge is a human concept. If a clean cat suddenly starts going outside the tray, it is reporting a problem — your job is to find which one.

Step 1. Rule out health. Always first

Roughly half of cases have a medical cause. The cat hurts in the tray, associates the tray with pain, and starts looking for somewhere else.

Other common medical causes: cystitis, urinary stones, kidney problems, joint pain in older cats (climbing over a high rim simply hurts), and digestive disorders.

Step 2. Check the tray itself

Very often the cause is so mundane that nobody notices it.

• Number. The rule: one more tray than you have cats. Two cats, three trays.
• Size. The tray should be about one and a half times the cat's length. Most shop trays are too small.
• Cleanliness. Many cats refuse a tray that already has something in it. Scoop daily.
• Washing. Harsh chlorine or citrus cleaners repel cats. Warm water and plain soap are enough.
• Lid. Covered trays suit people, but many cats find them cramped and stuffy. Try taking the roof off.
• Location. Not next to the food bowl, not by the washing machine, not in a thoroughfare. A cat needs to see who is coming.

Step 3. The litter

Cats have strong texture preferences. Most prefer fine, unscented clumping litter — it is closest to natural sand. Scented litters are made for humans; to a cat's nose they are often unbearable.

If you need to change litter, do it gradually: mix the new into the old over a week or two rather than switching at once.

Step 4. Stress

Cats are extremely sensitive to change. The trigger may be something you consider trivial:

• a move, renovation, new furniture;
• a new animal or a new person in the home;
• a change in your schedule;
• a strange cat walking past the window;
• loud noises, construction, fireworks;
• conflict with another cat in the flat — often hidden, with no visible fights.

What helps: a predictable routine, more vertical space and hiding places, daily hunting play, and separate resources for each cat (own bowls, trays and beds in different places).

Marking is something different

The distinction matters. When a cat toilets outside the tray, it squats and leaves a puddle on a horizontal surface. When marking, it stands, the tail quivers, and a small amount of urine goes onto a vertical surface: a wall, furniture leg or door.

Marking is territorial behaviour, most often linked to stress or to being unneutered. Neutering significantly reduces or eliminates marking in most cats.

Cleaning: a critical detail

Ordinary cleaners do not remove the smell for a cat's nose — they remove it for yours. The cat still detects the mark and returns to the same spot.

• Use enzymatic cleaners made specifically for animal marks.
• Never use ammonia-based products — urine contains ammonia too, so to a cat it reads as "toilet here".
• Temporarily put a food bowl, bed or tray on the favoured spot. Cats do not toilet where they eat and sleep.