Behaviour changes in cats
PetPort EditorialLast reviewed
Why has my cat's behaviour changed suddenly?
Cats do not sulk or act out. A cat that starts hiding, spraying, over-grooming or lashing out is telling you something has changed — pain, illness, or a threat to its territory. Because cats mask illness so well, a behaviour change is often the earliest symptom you will get.
General guidance for pet parents, not a diagnosis. Every animal is different — confirm anything that concerns you with your veterinarian.
Quick reference
| Rule out first | Pain, urinary disease, hyperthyroidism and dental disease |
|---|---|
| Litter-box avoidance | Medical cause more often than behavioural |
| Resource rule | One litter tray, food and water station per cat, plus one |
| Never punish | Spraying or hiding — it increases the stress that drives them |
| Senior cats | Sudden night-time yowling can be hyperthyroidism or cognitive decline |
What is happening
Behaviour is a cat's main way of reporting a problem. Hiding, litter-box avoidance, sudden aggression and compulsive grooming all have medical causes at least as often as social ones, and pain is top of that list.
Signs to watch for
- Hiding for long stretches in a cat that was previously sociable
- Urinating or spraying outside the tray
- Flinching, hissing or biting when touched or picked up
What you can do
- Book a veterinary examination before treating anything as behavioural
- Add vertical space — shelves and high perches genuinely reduce conflict
- Keep food, water and litter in separate, quiet locations
See a vet if
The change came on suddenly, your cat is hiding or aggressive when handled, has stopped using the tray, or is over-grooming to bare skin.
In India specifically
Territory pressure from free-roaming community cats is a major and under-recognised stressor for Indian house cats — a cat visible through a window grille can trigger indoor spraying by a cat that never goes out. Applying frosted film to the lower part of the window often resolves it. Festival firework noise is the other common trigger; prepare a quiet interior room in advance.
Common questions
Why is my cat suddenly hiding all the time?
Hiding is how cats respond to feeling unwell or unsafe. In a previously sociable cat it should be treated as a medical sign first — pain, fever and nausea all cause it. Check for other changes in eating, drinking and litter use, and book an examination.
My cat has started spraying indoors. How do I stop it?
First rule out a urinary problem, which mimics spraying closely. If it is genuine marking, it is a territorial stress response — a new cat outside the window, a new pet, or building work. Clean marked spots with an enzymatic cleaner, never ammonia-based, which smells like urine and invites repeat marking.
Why does my cat bite me during petting?
Many cats have a low threshold for sustained stroking and give clear warnings first — a twitching tail, flattened ears, skin rippling along the back. Stop at those signals rather than at the bite. A cat that has newly become touch-sensitive may be in pain and should be examined.
Is my old cat yowling at night because of dementia?
It can be feline cognitive dysfunction, but hyperthyroidism and high blood pressure cause the same night yowling and are common, treatable and easily missed. Any senior cat with new night-time vocalising deserves a blood test before it is put down to age.