Why cats are so good at hiding illness

Cats are built to conceal weakness. In the wild, a cat that looks unwell becomes a target, so the instinct to carry on as normal is deeply ingrained. In a warm, safe home that instinct works against them: by the time a cat looks obviously ill, whatever is going on has often been developing for weeks.

That is why the most useful skill for any owner is not spotting dramatic symptoms, but noticing small departures from your cat's own normal. Learn what normal looks like for your cat — how much they eat, how much they drink, how often they use the litter tray, how sociable they are at 7pm — and you will spot the quiet changes that prompt an early vet visit.

Changes in appetite, drinking and weight

A cat who usually polishes the bowl and starts leaving food is telling you something. Dental pain, nausea, stress and many illnesses all show up first as a change in eating.

• Leaving food, eating only when you crouch beside them, or abandoning a previously favourite food
• Eating more than usual while still losing weight — a classic pattern in older cats
• Chewing on one side, dropping food, or flinching when they eat

Drinking matters just as much. As a rough guide, a healthy cat drinks well under about 50ml per kilogram of bodyweight a day. If you are refilling the bowl noticeably more often, measure it — put a measured amount of water down in the morning and check what is left at night. Increased thirst is one of the earliest signs of kidney disease, diabetes and thyroid problems.

Weigh your cat monthly. A cheap kitchen scale with a sturdy box works well. Losing even five per cent of bodyweight — around 200g on a 4kg cat — is worth a phone call to your vet practice.

Litter tray clues

The tray is your best diagnostic tool, so pay attention to what you scoop.

• Urinating more often, in smaller amounts, or squatting for a long time
• Straining to pass urine, especially in male cats — if nothing is produced, this is an emergency and needs immediate veterinary attention
• Blood in the urine, a stronger smell than usual, or accidents on the carpet, bath mats or laundry
• Hard, dry stools, constipation, or diarrhoea lasting more than a day or two
• Messy fur around the back end, which often means a cat is struggling to reach or clean themselves

Behaviour, grooming and mobility

Cats rarely complain, but they do change their routines. Hiding under the bed, sleeping in odd places, or going quiet when visitors arrive can all be signs of pain or feeling unwell rather than simply "being a cat".

• Grooming less: greasy coat, dandruff, matting, or a scruffy, unkempt look
• Grooming more: bald patches on the flanks, belly or inner thighs
• Hesitating before jumps, missing the windowsill, or sitting rather than lying flat
• Stiffness, reduced jumping, or grumpiness when handled — arthritis is common in older cats and often mistaken for "just slowing down"
• Crankiness, withdrawal, or becoming clingy in a cat that was never that way

Physical signs worth checking at home

A quick once-over every week will help you catch changes early. Run your hands over the body, look inside the ears and mouth, and check the coat and claws.

• Eyes: dull, weepy, squinting, or the third eyelid showing at the inner corner
• Mouth: bad breath, drooling, red or bleeding gums, brown tartar, broken teeth
• Gums: pale, grey, blue or yellow colouring needs urgent attention
• Breathing: count breaths while your cat sleeps. Around 16 to 30 per minute is normal; consistently over 30, or any laboured or open-mouthed breathing, is urgent
• Coughing, wheezing, or a change in the sound of their meow
• New lumps, scabs, flea dirt, patches of hair loss or unexplained bruising
• Regular hairballs, or vomiting more than the occasional one-off

When to call your vet

Some signs need same-day attention. Contact your vet practice immediately if your cat has not eaten for 24 hours (12 hours for a kitten or a diabetic cat), is straining to urinate with little or nothing coming out, is having difficulty breathing, has collapsed, has sudden weakness in the back legs, is vomiting repeatedly, or may have eaten something toxic — lilies, antifreeze, human medicines and many household plants among them.

Other signs can wait a few days, but should not be left for months. Book an appointment if you notice gradual weight loss, increased drinking, persistent bad breath, poor grooming, a change in litter tray habits, or any behaviour shift that does not settle.

You know your cat better than anyone. If something feels off, ring the practice and describe what you have noticed — most are happy to advise over the phone, and a fifteen-minute check-up is far easier on both of you than waiting until a problem becomes an emergency.