Cat Diseases: Symptoms, Common Illnesses and When to See a Vet

Cats rarely make a fuss when they are ill. You usually notice it in small changes: your cat eats differently, drinks more, hides, grooms less or stops jumping onto the windowsill. If you are unsure, take your cat's temperature (normal is 38.1 to 39.2 °C) and phone your vet. If your cat has not eaten for a day, is struggling to breathe, or a male cat keeps straining without passing urine, go straight away. Below you will find a symptom checklist, the emergency signs, how to check for a fever, and a short guide to the most common cat diseases with links to our more detailed pages.

Is my cat ill? A symptom checklist

Cats are very good at hiding pain and illness. International Cat Care describes withdrawing and hiding as a typical response to pain. That is why you spot illness mainly by what has changed compared with normal. Go through this list. If you recognise one or more signs that have lasted longer than a day, or several at once, phone your vet.

What you notice	What it can point to	How urgent
Eats less, nothing, or differently (chews on one side, drops food)	Pain, dental disease, nausea, almost any illness	Phone after 24 hours without food, sooner for a kitten
Eats much more but loses weight	Overactive thyroid, diabetes	Appointment this week
Drinks and pees noticeably more	Kidney disease, diabetes, thyroid	Appointment this week
Strains in the litter tray, pees small amounts often, or pees outside the tray	Cystitis, crystals, in a male cat possibly a blockage	Male cat passing nothing: now. Otherwise the same day
Vomits more than occasionally, diarrhoea, or blood in the faeces	Gut problem, infection, poisoning, enteritis in a kitten	Same day if repeated or in a kitten
Hides, sleeps more, is dull or restless	Pain, fever, being generally unwell	Same day if it does not pass
Stops jumping, walks stiffly, grooms less	Pain, arthritis, excess weight	Appointment
Hisses or growls when you touch one spot	Pain, an abscess after a fight	Same or next day
Bad breath, drooling, pawing at the mouth	Dental disease, mouth inflammation	Appointment
Sneezing, runny nose, weepy eyes	Cat flu	Phone if eating poorly or a kitten
Breathes fast or hard at rest, coughs	Airways, asthma, heart disease	Laboured breathing: now
Soils the house, meows much more or behaves differently	A medical cause comes before a behaviour problem	Appointment

You know your cat best. A feeling that something is off is a good enough reason to phone, even if you cannot put your finger on it. A cat that suddenly sleeps all day is also worth a closer look, and why cats sleep so much explains what is normal. A calm cat that suddenly starts biting may be in pain, as we describe in why does my cat bite me.

Reading pain in your cat's face

Vets use the Feline Grimace Scale, a validated tool for reading acute pain from a cat's face. Look for ears turned outwards or flattened, squinted eyes, a tense muzzle and whiskers pointing straight forward or pulled back. A cat in pain often sits hunched with its head held low.

When is it an emergency?

With any of the signs below, phone your vet straight away. Outside opening hours your own practice will refer you to an out-of-hours emergency vet. Always phone ahead so they know you are coming.

• Breathing difficulty. Open-mouth breathing, panting, or more than 35 breaths a minute at rest (the threshold used by the Cornell Feline Health Center). The PDSA lists pale, grey or blue gums and a sudden decline as reasons to go immediately.
• A male cat straining without passing urine. This is how a blocked urethra looks. International Cat Care warns that a blockage can be fatal within two to three days. Owners often mistake it for constipation.
• Collapse, unresponsiveness or a seizure that lasts longer than five minutes or keeps coming back (International Cat Care). Even if your cat recovers quickly, phone your vet afterwards, the PDSA advises.
• Poisoning or suspected poisoning: paracetamol, ibuprofen, lilies (even pollen licked off the coat can cause kidney failure), antifreeze, or a dog flea product containing permethrin. Do not wait for symptoms. In the UK, the Animal PoisonLine run by the Veterinary Poisons Information Service gives 24-hour telephone advice to owners. For foods that are dangerous, see what human food can cats eat.
• Overheating: your cat was shut in a warm room or car, is panting and floppy. Above 40 °C a cat is at risk of heatstroke (PDSA). Move your cat somewhere cool and phone straight away.
• An accident, a fall, heavy bleeding, or a cat that suddenly cannot use its back legs.
• A kitten that is not eating or drinking, or is vomiting or has diarrhoea. Kittens dehydrate fast and infectious enteritis is often severe in them.

Normal cat temperature and how to check for a fever

You cannot reliably tell whether your cat has a fever by feeling its nose. A warm, dry nose means very little. The PDSA does list signs that fit with a fever: ears, feet or face feel hot, your cat hides, will not eat, shivers or breathes faster than usual. Only a thermometer gives you certainty.

Temperature	What it means
38.1 to 39.2 °C (100.5 to 102.5 °F)	Normal (Merck Veterinary Manual). A cat that has just been stressed by the journey to the vet can read slightly higher.
39.3 to 39.5 °C	Raised. Keep a close eye and measure again later, especially if your cat is also eating less or withdrawing.
From 39.5 °C (103 °F)	Fever. Most cats with a true fever sit between 39.5 and 41.1 °C (Merck). Phone your vet.
Above 40 °C	High. After a warm room or car this can be heatstroke (PDSA). Phone straight away.
Below 38 °C in a weak, floppy cat	Possibly hypothermia, which the PDSA treats as an emergency. Phone straight away.

How to take your cat's temperature

1. Use an ordinary digital thermometer, ideally one with a flexible tip, and keep it for your cat only.
2. Ask someone to hold your cat calmly on a lap or on a towel on the table.
3. Put a little petroleum jelly on the tip so it slides in more easily.
4. Lift the tail and gently insert the thermometer into the rectum with a slight twisting motion, just far enough to get an accurate reading.
5. Wait for the beep and read it. Clean the thermometer with soap and water or alcohol.

If your cat struggles hard or panics, stop. If you are going to the vet anyway, the nurse can take the temperature there.

Never give paracetamol or ibuprofen

Never give your cat medicines meant for people. International Cat Care calls paracetamol extremely toxic to cats. Cats cannot break it down safely, which damages the liver and red blood cells. Even part of one tablet can cause severe poisoning and death. The same charity warns that ibuprofen and aspirin are also highly toxic and can be life-threatening. A child's dose or "just a little bit" is dangerous too. If your cat has had any, phone your vet now. Signs such as brownish gums, weakness, fast breathing and vomiting usually appear within 4 to 24 hours.

A fever is the body's response to infection, inflammation or pain. Your vet treats the cause and, where needed, gives a painkiller or fever reducer that is safe for cats. What you can do at home:

• Put fresh water close by, preferably in a few places.
• Offer something tasty. Slightly warmed wet food smells stronger and tempts better.
• Give your cat a quiet, draught-free spot to retreat to, such as a covered bed or a cardboard box with a blanket.
• Write down the temperature, what your cat eats and drinks, and whether it pees. Your vet will find this useful.

Wetting your cat or cooling it down is only for heatstroke, never for an ordinary fever.

Common cat diseases at a glance

A large study from the Royal Veterinary College (VetCompass) looked at the records of 18,249 cats seen in UK first-opinion practices in 2019. The most frequently recorded problems were gum disease (15.2%), obesity (11.6%), other dental disease (9.2%), overgrown nails (5.2%), flea infestation (5.1%) and a heart murmur (4.4%). Older cats had more conditions than younger cats. In other words, the everyday problems are far more common than the frightening viruses, and many of them can be prevented.

Disease	Typical signs	Who gets it most
Dental disease	Bad breath, drooling, chewing on one side, dropping food	Adult and older cats
Cat flu	Sneezing, runny nose and eyes, mouth ulcers	Kittens, unvaccinated cats, multi-cat homes
Infectious enteritis (panleukopenia)	Fever, vomiting, diarrhoea, dehydration, sudden death	Unvaccinated kittens
Chronic kidney disease	More thirst and urine, weight loss, poor appetite	Older cats
Diabetes	More thirst and urine, weight loss despite a good appetite	Middle-aged and older, overweight cats
Hyperthyroidism	Ravenous yet losing weight, restless, fast heart	Cats over about 7 years
FIV and FeLV	Recurrent infections, gum inflammation, weight loss	Outdoor cats, unneutered males (FIV)
FIP	Persistent fever, swollen belly or breathing trouble, wobbly gait	Cats under 2, often 4 to 12 months
FLUTD (bladder problems)	Straining, small frequent pees, blood in urine	Indoor, overweight and stressed cats
Worms and fleas	Itching, pot belly in kittens, diarrhoea, "rice grains" by the bottom	All cats, kittens especially

Dental disease

Dental disease is the most common problem in UK cats according to the RVC study, and the Cornell Feline Health Center estimates that 50 to 90% of cats over four have some form of it. The three best known are gingivitis, periodontitis (inflammation of the gums and the bone around the teeth) and tooth resorption, where a tooth is broken down from within. Resorption can be very painful. Watch for bad breath, drooling, chewing on one side, dropping food, tilting the head while eating or only wanting soft food. Ask your vet to check the teeth at every annual check-up.

Obesity

The second most common diagnosis in the RVC study, and male cats were more at risk. Excess weight increases the chance of diabetes, arthritis and bladder problems. Your vet can tell you your cat's ideal weight and how much to feed. For the basics of a good diet, read the importance of good cat food.

Cat flu

Cat flu is the common name for infections of the nose, eyes and throat, mostly caused by feline herpesvirus and feline calicivirus. Your cat sneezes, has a runny nose and weepy or inflamed eyes, and sometimes ulcers in the mouth. It spreads easily between cats. Cats with a blocked nose cannot smell their food and often stop eating, so phone your vet if your cat eats poorly, and always if it is a kitten. The core vaccination protects against severe illness. Many cats that recover from herpesvirus carry it for life and can have flare-ups during stress.

Feline infectious enteritis (panleukopenia)

A highly contagious parvovirus and a different illness from cat flu. Signs appear within a few days of infection: lethargy, fever, not eating, vomiting and diarrhoea, which quickly lead to dehydration. Kittens can die suddenly, and many unvaccinated cats do not survive even with intensive treatment. The virus is very hardy and can survive in the environment for up to a year, so it can reach indoor cats on contaminated items. That is why the PDSA advises vaccinating every cat in the UK against it, including cats that never go out.

Chronic kidney disease (CKD)

One of the most common diseases in older cats. International Cat Care estimates that 20 to 50% of cats over 15 have some degree of it, and Cornell gives even higher figures. Early on you often see nothing. Later your cat drinks and pees more, eats less, loses weight and its coat looks scruffy. CKD cannot be cured, but it can often be slowed with a kidney diet, enough fluid and blood pressure checks. International Cat Care recommends a yearly or six-monthly check with blood and urine tests for older cats. A health monitoring cat litter can give an early nudge between check-ups, but it is never a diagnosis. For what to expect as your cat gets older, see how long do cats live.

Diabetes

One of the most common hormone diseases in cats. According to International Cat Care, middle-aged and older cats, males, neutered cats and especially overweight cats are most at risk. The classic signs are drinking more, peeing more and losing weight while eating more. Some cats start walking flat on their hocks. If a diabetic cat becomes dull, vomits or collapses, that is an emergency. Treatment involves insulin or, for some cats, newer oral medication, a low-carbohydrate diet and weight loss. In some cats the diabetes goes into remission when they lose weight and get the right food.

Hyperthyroidism (overactive thyroid)

Seen almost only in middle-aged and older cats, rarely under seven (International Cat Care). Your cat eats ravenously yet loses weight, drinks more, is restless or irritable, has a fast heart rate and a greasy, unkempt coat. Some cats vomit or have diarrhoea. There are good treatments: tablets, a special diet, surgery, or a single radioactive iodine treatment that cures most cats.

FIV (feline immunodeficiency virus) and FeLV (feline leukaemia virus)

FIV weakens the immune system. It spreads mainly through bite wounds, so outdoor cats and males (around twice as often as females) are most at risk, according to International Cat Care. After a short phase of fever and swollen lymph nodes, many cats show nothing for years. Later, recurrent infections, gum inflammation, weight loss and diarrhoea can follow. Diagnosed early, many FIV cats live for years without FIV-related illness. A vaccine exists in a few countries, but there is none licensed in the UK or the rest of Europe, so neutering and fewer fights are the main protection.

FeLV spreads more easily, through saliva during close, long-term contact: mutual grooming and shared bowls and litter trays. You see fever, lethargy, weight loss, pale gums and repeated infections, and the virus often causes anaemia or cancer. International Cat Care estimates that 80 to 90% of infected cats die within three to four years of diagnosis. Vaccines against FeLV are available, and the PDSA recommends them for UK cats that go outdoors, even just into the garden. Your vet can test for both viruses with a quick blood test, for example when you take in a new or stray cat.

FIP (feline infectious peritonitis)

FIP develops when a common feline coronavirus mutates inside the body. International Cat Care reports that around 80% of cases are in cats under two, many of them kittens of 4 to 12 months, and cats from multi-cat settings such as breeders and rescues are more at risk. In "wet" FIP fluid builds up in the belly or chest (a swollen tummy, breathing trouble). In "dry" FIP inflammation develops in organs, with signs such as a wobbly gait, behaviour changes or eye problems. Early signs are vague: a fluctuating fever that does not respond to antibiotics, lethargy and a poor appetite.

FIP used to be almost always fatal. That has changed. Since 2021, UK vets have been able to prescribe antivirals legally: remdesivir by injection and GS-441524 as tablets or liquid, usually for a course of around 12 weeks. International Cat Care reports that more than 85% of treated cats are cured. Treatment is expensive, so ask your vet about the options and costs early. Avoid unlicensed products bought online, whose content and strength are unknown.

FLUTD (bladder and urinary problems)

Straining, peeing small amounts often, blood in the urine or peeing outside the tray: International Cat Care groups these as feline lower urinary tract disease. In 60 to 70% of cats no clear cause is found (idiopathic cystitis), and stress plays a big part. Crystals and stones also occur, while a bacterial bladder infection is fairly rare in cats. More water and wet food help prevent it. In a male cat that cannot pass urine, it is a blockage and an emergency. If your cat is peeing outside the tray, how to get rid of cat pee smell helps you clean up so the spot does not become a habit, and why is my cat pooping outside the litter box covers the medical and stress causes of toileting problems.

Parasites: worms, fleas and ear mites

Fleas were the fifth most common problem in the RVC study. They cause itching and can pass on tapeworm, and a heavy infestation can make a kitten anaemic. Roundworms give kittens a pot belly and diarrhoea, and kittens usually get them through their mother's milk. Tapeworm segments look like grains of rice around the bottom. Ear mites cause itching and dark, crumbly ear wax. Which wormer to use, what you can buy over the counter in the UK and how often to treat is all in the best cat dewormers. One rule for flea treatment: never use a dog product on a cat.

Heart disease (HCM)

Hypertrophic cardiomyopathy is the most common heart disease in cats. It often shows no signs until it is advanced, and cats with heart disease rarely cough. Watch for fast or laboured breathing at rest, weakness and sudden lameness in the back legs, which can mean a blood clot and is an emergency. Some breeds carry a higher risk. Read more in our guides to the Maine Coon and the Ragdoll.

Vomiting, diarrhoea and not eating

These are symptoms with many possible causes, from a hairball to a serious illness. A cat that has not eaten for 24 hours needs a vet. International Cat Care warns that even a few days without enough food can have serious consequences and makes every illness worse. Read cat not eating: causes and solutions for the details. If your vet has ruled out illness and your cat simply has a sensitive gut, the best cat food for sensitive stomachs explains which diets help.

Kitten diseases and health problems

Kittens get ill faster and more seriously than adult cats because they have small reserves and a developing immune system. The most common problems are:

• Roundworms and fleas. Almost every kitten has roundworms from its mother's milk. Worm from the age your vet or the product allows (see cat dewormers) and check for fleas.
• Cat flu. Common in kittens from breeders, rescues and multi-cat homes. A kitten with a blocked nose stops eating quickly, so phone your vet early.
• Infectious enteritis. The most dangerous illness for unvaccinated kittens. Vomiting, diarrhoea and lethargy in a kitten are always a reason to phone the same day.
• Diarrhoea from a change of food or stress. Keep your kitten on the food it was used to for the first weeks and change slowly. Diarrhoea that lasts longer than a day, or comes with lethargy, needs a vet.
• FIP shows up most often between 4 and 12 months.

According to the PDSA, kittens in the UK usually have their first vaccinations at around 9 and 12 weeks, some need a third injection at 15 weeks, and they then need a booster. Your vet will set the exact schedule.

What happens at the vet

The vet starts with questions: since when, is your cat eating and drinking, peeing and pooing normally, does it go outside, is it vaccinated. So bring your notes, and a photo or video of what you have seen. A physical examination follows, with temperature, heart and lungs, belly, mouth and weight. Depending on what is found, blood tests, a urine test, an FIV and FeLV test, an ultrasound or an X-ray may follow. Take your cat in a sturdy carrier that closes properly. A sick cat that escapes is hard to find. Tips for a calm journey are in how to travel with a cat by car.

Tests and treatment can add up, especially for a long-term illness. Pet insurance taken out while your cat is still healthy usually covers more, because existing conditions are often excluded.

Caring for a sick cat at home

• Rest and a place of its own. A warm, sheltered spot where other pets and children leave your cat alone, with water, food and the litter tray close by.
• Offer food. Small portions, slightly warmed, several times a day. Do not force-feed without talking to your vet.
• Give medicines exactly as prescribed. Finish a course of antibiotics even if your cat seems better, and follow the label or your vet's advice. If tablets are a battle, how to give a cat a pill walks you through it.
• Keep a record. Eating, drinking, peeing, pooing and temperature. A downward trend is a reason to go back sooner.
• Contagious? With cat flu and enteritis, keep other cats apart and wash your hands after every contact.

If your cat does not improve within two to three days, or gets worse, always go back to the vet, even if it seemed minor at first.

Preventing disease

• Vaccinate, including indoor cats. The PDSA advises that all cats in the UK are vaccinated against cat flu and infectious enteritis, and that cats going outdoors are also vaccinated against FeLV. Boosters keep the protection going.
• A yearly check-up, and more often for older cats or cats with a condition. Kidney disease, thyroid problems and dental disease are often found before your cat shows signs.
• A healthy weight and good food. Obesity raises the risk of diabetes, arthritis and bladder problems.
• Neutering. Unneutered males fight more, which is how FIV spreads.
• Regular worm and flea treatment, and keeping human medicines, lilies, antifreeze and dog flea products out of reach.
• Trim overgrown nails. They were the fourth most common problem in the RVC study. See the best cat nail clippers and how to use them.

Frequently asked questions