A cat may have a fever if they are unusually tired, hiding, eating less, shivering, breathing faster than normal, vomiting, passing diarrhoea, or generally seeming "not themselves". But the only reliable way to confirm a fever is to check their temperature with a thermometer.

A normal cat temperature is usually around 38–39°C. Any temperature above 39.5°C is considered high and should prompt veterinary advice. Remember, fever is not an illness in itself, but it is usually a sign that the body is responding to some kind of underlying problem.

In this guide, we look at everything you need to know about how to tell if your cat has a fever and what to do if you discover one.

What Is a Fever in Cats?

When a cat has a fever, its body temperature is higher than normal. As mentioned, a normal cat body temperature is approximately 38–39°C, and anything above 39.5°C is considered a high temperature.

The terms "fever" and "high temperature" are often used interchangeably. Very high temperature, persistent fever or fever with other worrying symptoms should prompt urgent vet advice. A fever usually happens because the body is responding to another issue.

Hyperthermia is slightly different. It usually happens when a cat overheats, such as during heatstroke. When a cat has a fever, you will usually notice behavioural changes like seeming withdrawn or quiet.

Signs Your Cat May Have a Fever

If you are wondering how to tell if your cat has a fever, the only accurate answer is by taking its temperature with a thermometer. But there are various telltale signs that a cat is unwell that might prompt you to do that:

• Lethargy or sleeping more than usual
• Hiding away or avoiding people
• Reduced appetite or refusing food
• Drinking less or showing signs of dehydration
• Shivering or trembling
• Warm ears, paws or body, though touch alone is not reliable
• Faster breathing or panting
• Vomiting
• Diarrhoea
• Reduced grooming or a scruffy coat
• Bright pink or red gums
• Irritability, clinginess or unusual behaviour

Not every cat with a fever will show all of these symptoms. What's more, some signs (like warm ears) can happen for reasons other than a fever. The first clue is usually behaviour changes.

How to Check If Your Cat Has a Fever

The most accurate way to confirm a fever is with a thermometer. Vets commonly use a rectal thermometer because it gives the most reliable reading. If you are attempting to take your cat's temperature yourself, here are some tips:

• Use a digital thermometer — it's faster
• Apply a suitable lubricant if taking a rectal temperature
• Keep the cat calm and handle them gently
• Stop if the cat becomes distressed, aggressive or difficult to handle
• Contact your vet if unsure

Ear thermometers and feeling the ears, nose or paws are not always reliable ways to check. A dry nose is not proof that your cat has a fever. If you aren't confident in taking your cat's temperature safely, call your vet for advice rather than risking injury or distress.

When Should You Call the Vet?

A fever is usually something that should be checked by a vet, as it can sometimes be a sign of a serious illness in cats. It's important to know when to contact a vet, so here is some guidance. Contact your vet if:

• Your cat's temperature is above 39.5°C
• Symptoms last longer than 24 hours
• Your cat is refusing to eat or drink
• Your cat is very lethargic, weak or collapsed
• Your cat has vomiting or diarrhoea
• Your cat is breathing quickly, panting or disorientated
• You suspect poisoning or heatstroke
• Your cat is a kitten, elderly, pregnant or has an existing health condition

There are certain red flags to look out for when your cat is urinating. These include straining, crying while trying to urinate or obvious signs of blood in the litter tray. Litter Sense cat litter changes colour when urine contains blood or has the wrong pH balance — this can give you an early warning sign that something is wrong.

If a male cat is straining or unable to pass urine, this could be a sign of urinary blockage. This is an emergency.

What Causes Fever in Cats?

Fever is usually a symptom of an underlying problem. There are many things that might be behind a fever in a cat, but here are some common causes:

• Bacterial or viral infections
• Cat flu and respiratory infections
• Infected bite wounds or abscesses, especially in outdoor cats
• Urinary tract infections
• Dental infections
• Inflammation or pain
• Pancreatitis
• Toxins or poisoning
• Heatstroke
• Medication reactions
• Immune-mediated disease
• Tumours or more serious underlying illness

Because the causes range from mild to serious, it is important not to guess based on symptoms alone. Outdoor cats may be more exposed to things like fights, infected wounds and parasites. Indoor cats can still develop infections, urinary problems, dental disease and more.

What Will the Vet Do If Your Cat Has a Fever?

When you take your cat to the vet, they will try to find the underlying cause rather than simply "treating the temperature". They will likely carry out a physical examination and a temperature check. They may also listen to the heart and lungs, check gums and look for wounds or abscesses.

Further diagnostic tests may be needed to find the underlying cause, depending on symptoms. These can include:

• Blood tests
• Urine testing
• Faecal testing
• X-rays
• Ultrasound
• Testing for infections

Treatment options vary depending on what is causing the infection. The vet may recommend fluids for dehydration or antibiotics if a bacterial infection is confirmed. Pain relief or anti-inflammatory medication may be prescribed, and further treatments for underlying illness could be pursued.

In severe cases, hospitalisation can be an option. Owners should never use human medicines to reduce a cat's temperature.

How to Care for a Cat With a Fever at Home

Any home care for an unwell cat should be done in line with the advice of your vet. Often, it is recommended to keep the cat indoors, warm, quiet and comfortable. Fresh water and palatable food are usually recommended as well.

In most cases, you will be advised to keep food, water and the litter tray nearby. Monitor your cat's appetite, drinking, energy levels and breathing and keep checking for vomiting, diarrhoea or signs of pain. Complete any prescribed medication course.

Hydration is a key consideration. Cats with fever can become dehydrated — wet food is often helpful to support fluid intake if the cat is happy to eat. If you notice your cat getting worse or developing breathing problems, contact your vet urgently.

Can Litter Tray Changes Help You Spot Illness?

Litter tray changes cannot confirm a fever — fever is confirmed by measuring body temperature. Nevertheless, litter tray monitoring is an important consideration.

Ill cats may drink more or less than usual. They may also urinate more often, pass smaller amounts, strain, or avoid the tray altogether. Urinary problems often appear alongside general signs of illness, such as:

• Lethargy
• Reduced appetite
• Hiding

Look out for your cat taking more or fewer trips to the litter tray. A stronger urine smell, blood in the urine, or straining to urinate may be signs of an issue as well. Litter Sense cat litter is not a fever test, but it may help catch signs of an underlying problem before you even detect a fever.

What Not to Do If You Suspect Your Cat Has a Fever

You must not give paracetamol, ibuprofen, aspirin or any human fever medication to a cat unless prescribed by a vet. It isn't a good idea to try to cool your cat rapidly with ice baths or cold water.

Here are a few more things not to do:

• Don't ignore a cat that is not eating, hiding, vomiting, struggling to breathe or unable to urinate
• Don't assume a warm nose or ears is proof of a fever
• Don't delay calling a vet if symptoms are severe or persistent

Fever can be a sign of a serious underlying condition that needs to be treated. Human medicines are a bad idea because many are toxic to cats, and rapid cooling can cause stress or even shock.

Frequently Asked Questions About How to Tell If Your Cat Has a Fever

Can you tell if a cat has a fever by touching their ears?

Warm ears can be a clue, but they are not reliable for diagnosis. Cats can feel warm because of room temperature, stress, exercise or sitting in the sun. A thermometer is the only reliable way to confirm.

Can a cat fever go away on its own?

Mild fever may improve if the underlying cause resolves itself, but owners shouldn't rely on this. Contact a vet if the symptoms last more than 24 hours or the cat seems very unwell. Fever with vomiting, diarrhoea, breathing difficulty, collapse, pain or urinary problems needs urgent attention.