Why is my cat not using the litter box?

Litter box avoidance is the single most common behavioural problem reported in cats, and it is the leading reason cats are surrendered to shelters. The most important first step: rule out a medical cause before assuming it is behavioural.

Medical causes to rule out first

- Urinary tract infection (UTI) — painful urination outside the box is extremely common and requires antibiotics
- Feline idiopathic cystitis (FIC) — inflammation of the bladder with no bacterial cause, triggered by stress. Very common in indoor cats.
- Urinary crystals or stones — cause painful urination and straining. A male cat that is straining to urinate and producing little or no urine is a medical emergency — urethral blockage is life-threatening.
- Kidney disease, diabetes, hyperthyroidism — all increase urination frequency
- Arthritis — older cats may avoid a box with high sides because climbing in is painful
- Constipation — if defecating outside the box only, constipation is common in senior cats

The litter box rules (behavioural causes)

If medical causes are ruled out, assess the box setup:

- Number — one per cat, plus one extra. A single box for two cats is frequently a source of conflict.
- Size — most commercial boxes are too small. The box should be 1.5× the length of the cat. Many cats prefer uncovered boxes (covers trap odour and restrict exit routes).
- Location — quiet, accessible, away from food and water. Not near noisy appliances. Cats will not use a box they cannot approach safely.
- Cleanliness — scoop at least once daily. Cats are fastidious — a dirty box is rejected.
- Litter type — sudden changes in litter type cause avoidance. If you need to switch, do it gradually. Most cats prefer fine-grained, unscented clumping litter.

Flovvi tip

Track litter box incidents in Flovvi — note the location, frequency, and whether urine or faeces is involved. This information is essential for your vet to differentiate medical from behavioural causes.