Cats with fever

Written by Indy | July 31, 2025

Just like humans, cats can also get a fever. But what exactly is a fever? How can you recognise it? And what should you do if your cat has a fever? You’ll find all the answers in this article about fever in cats.

When does a cat have a fever?

Cats are warm-blooded animals and have a constant body temperature. A normal temperature ranges between 38 and 39.5 degrees Celsius, which is higher than in humans. When a cat has a fever, its body temperature is elevated. This temperature can already increase by 0.5 to 1 degree due to stress or physical exertion.

How can you tell if a cat has a fever?

A fever is not a disease, but a defence mechanism of the body in response to, for example, an infection. However, your cat’s body temperature can also be elevated when it is unable to lose excess heat properly, which is called overheating. In addition to overheating, temperature can rise due to exertion, stress, increased metabolism or hormonal changes. So, an elevated body temperature is not always the same as a fever.
You can measure your cat’s body temperature using a thermometer. This is done rectally. For an accurate reading, the thermometer should be inserted deep enough — around 2 cm. To make this easier, you can lubricate the thermometer with something like petroleum jelly. Only read the temperature once the thermometer has finished measuring.

Symptoms of fever in a cat

Shivering
Increased heart rate
Rapid breathing
Muscle weakness
Reduced appetite
Elevated body temperature
Disrupted fluid and electrolyte balance

Warm ears in your cat can be a sign of fever, but they can also simply result from lying in the sun or feeling a bit warm temporarily. In that case, it’s good to help your cat cool down.

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Causes of fever in cats

Fever is actually a reaction of the body to foreign cells entering your cat’s system. The immune system becomes active, and white blood cells are triggered, which in turn alert the brain. This causes the body temperature to rise. A higher body temperature makes it harder—or even impossible—for an intruder, such as a bacterium or virus, to multiply. This helps the body fight off the invader more effectively. The immune system can be activated by bacteria, viruses, fungi, parasites, toxins, tumours, or autoimmune diseases.

Treatment of fever in a cat

Does your cat have a fever? It is important to identify the underlying cause. Your veterinarian can carry out examinations to determine a diagnosis and start targeted treatment. They can also provide fever-reducing medication. Never give paracetamol or aspirin yourself! These are highly toxic to cats. The advice is therefore to always contact your veterinarian if your cat has a fever. Fever is a healthy bodily response to a pathogen, but a very high fever (above 41 degrees Celsius) can be dangerous for organs such as the heart and kidneys.

Cat has a fever and is not eating

If your cat is eating or drinking very little—or not at all—it may be necessary to force-feed your cat or place a feeding tube. Due to the high body temperature, your cat’s energy needs increase and it also loses more fluids. In the case of dehydration, your cat may need to be supported with a fluid infusion. If in doubt, always contact your veterinarian.

Do you have any questions about fever in cats? Please contact veterinarian@vetsend.co.uk.