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Tierambulatorium Wienerberg

This article was written by TOBALIE in cooperation with Tierambulatorium Wienerberg

If you have ever been in bed with a fever, you can probably understand how unpleasant this feeling can be. A very high fever is a real strain on the body and requires a lot of energy. Among other things, you feel very weak and depressed, struggle with headaches and aching limbs, your pulse races and your appetite seems to be blown away.

When our beloved cats have a (high) fever, they are most likely not doing well either. Very high fevers can even be life-threatening for your little darling. But how can you tell if a cat has a fever? And what can owners do to support their cat’s weakened body?

What is fever?

First of all, let’s look at the question of what a fever actually is: Fever, also called pyrexia in medicine, is not a disease in its own right. It is always a symptom, a natural defence reaction of the body. Higher temperature or fever supports the immune system in fighting various pathogens and co. The level and duration of the fever are sometimes dependent on the type and number of pathogens, or on the severity of the illness.

The duration of the fever determines how the fever is categorised:

  • Ephemeral fever: Usually lasts only one day.
  • Acute fever: Up to 2 weeks
  • Subacute fever: 2 to 3 weeks
  • Chronic fever: From 3 weeks 

Fever can also rise (or fall) continuously or occur in episodes. Between the relapses, there is usually a so-called recurrent phase. During this phase, the patient on four paws is usually free of fever.

Good to know: If you notice that your cat has a fever, you do not have to panic immediately. Short-term and moderate fever are usually well tolerated by a healthy and strong cat’s body. Fever-reducing medication is not always advisable, as fever naturally works against the cause by boosting the immune system. The veterinarian decides whether treatment is necessary.

Caution: Long-lasting and/or very high fever can lead to serious physical problems and should be treated immediately. In older or very young animals, as well as in already weakened and/or previously ill cats, you should also act quickly and consult a veterinarian to clarify the cause and alleviate the symptoms.

At what body temperature do cats have a fever?

Compared to humans, cats have a much higher normal temperature. The normal body temperature of adult cats is usually between 38 and 39.3 degrees celsius. Kittens usually have a higher normal temperature, up to 39.5 degrees celsius. 

However, the temperature may fluctuate more often throughout the day, depending on whether the cat is resting or moving around intensively. Possible stress and/or a high outside temperature also have an influence on a higher body temperature.

A (adult) cat is said to have a fever from a value of 39.2 degrees celsius, from a value of 41 degrees celsius it can become life-threatening for our graceful friends. At this body temperature, vital proteins are destroyed.

What are the causes of fever in cats?

Fever is therefore a natural defence process of the immune system. For a healthy cat, a moderate fever is not dangerous at first. However, a fever is an indication that certain processes are going on in your pet’s body that need further professional investigation. Especially if your cat shows other symptoms of a disease (see below).

Unfortunately, it is usually impossible for us as laypeople to determine what the causes are, as the range of possibilities for why the cat is feverish is very broad:

  • Infections with viruses  (leucosis, feline AIDS, feline coronavirus, cat cold).
  • Infections with bacteria
  • Parasite infestations
  • Fungal infections
  • Toxic plants and food, chemicals
  • (Chronic) inflammations 
  • Immune-related diseases (rheumatism, arthritis)
  • Vaccination reaction (usually only briefly)
  • Side effect of medication
  • Heat stroke
  • Stress
  • Tumours
  • Allergies
  • Bite injuries
  • And more.

How do I know that my cat has a fever?

When we humans think we have a fever, we instinctively reach for a clinical thermometer, which will tell us shortly. Unfortunately, our furry pets cannot speak and tell us when they are not feeling well. This is where our powers of observation come in. 

Since fever as a symptom rarely occurs alone, the following signs can be indications of a high temperature rise in your cat: 

  • Changes in behaviour: Your previously alert and active cat suddenly seems very tired, depressed and listless, avoiding any exertion? Your usually very affectionate cuddly cat is creeping away or your rather shy roommate suddenly won’t leave your side? Your previously tame companion suddenly turns into a wild beast? If your darling suddenly shows untypical behaviour, this can be an indication. 
  • Some cats suddenly prefer a cooler place to lie down. 
  • Apathy.
  • Changes in eating behaviour: Feverish cats usually lose their appetite.
  • Instead, the desire to drink usually increases.
  • Intestinal activity decreases, dry and very solid faeces may develop (“fever faeces”).
  • Diarrhoea and vomiting are also possible.
  • Sneezing and coughing.
  • Shivering. 
  • Increased panting and/or purring. Purring is not exclusively a sign of well-being!
  • Increased respiratory rate, increased pulse.
  • Stiffened muscles and joints.
  • Nose and ears feel very warm.
  • The nose is also very dry, and nasal secretions may be discharged.

Sometimes a fever in a cat only shows 1-2 symptoms, sometimes unfortunately they suffer from the whole range of possible symptoms.

To determine the exact body temperature, a thermometer is also used in animals. This is usually inserted rectally. Please only use a special clinical thermometer for cats.

Good to know: A rectal measurement is unpleasant for some cats. Some even resist with their hands and feet – or rather with all their paws. Ask a second person to help you with the measurement by carefully holding and securing your pet or distracting him with tasty food. Grease the tip of the thermometer with vaseline to make the measurement more comfortable.

When should I take a fevered cat to the vet?

So fever can manifest itself in many different ways, but how do you as an owner know when a visit to a veterinary clinic becomes urgent?

  • Fever over 40 degrees celsius.
  • Long-lasting moderate fever (longer than 3 days).
  • In kittens or older animals.
  • In weakened and/or previously ill animals.
  • In chronically ill cats.
  • If your pet seems apathetic or unresponsive.
  • Noticeable pain in the cat.
  • Severe trembling and/or panting.
  • Any sudden further deterioration of the general condition.

Important: If you are unsure, contact your veterinarian to clarify the situation. 

What can I do if my cat has a fever?

One thing is certain: as a loving owner, you quickly feel sorry for your cat when he or she is visibly unwell. It is absolutely understandable that you then pull out all the stops as quickly as possible to ensure that your furry friend is well again as soon as possible. 

 It is always advisable to consult a veterinary surgeon, especially if one of the points listed in the last paragraph applies to your cat. You should also waste no time if your fevered friend’s condition continues to deteriorate. This also applies to healthy and robust cats. 

 Short, mild fevers are usually not dangerous – and as you now know, natural and sensible – and often do not require treatment. After consulting your vet, you can help your cat with the following tips:

  • Your darling needs a lot of rest now: Avoid big commotion, big efforts. Make sure that your darling can withdraw. A cool, darkened room is a good place for this.
  • Cats that are used to being outdoors should be observed at home. Only when the cat is visibly feeling better can you let it outdoors again.
  • Make sure that your cat has enough water available. Adequate water intake is very important at this time.
  • If your cat doesn’t like food at all, you can try offering him licking pastes or similar. 
  • Damp, cool compresses around the paws can help.
  • Take the temperature at regular intervals.

Important: Please never try to treat your cat on your own with medicines from your medicine cabinet!

Katze Fieber


Fever is a natural reaction of the immune system to mobilise the body’s defences. The increased temperature effectively fights off pathogens and the like. Low fever in previously healthy and adult cats usually disappears by itself and only requires (after veterinary consultation) a lot of rest and a sufficient water supply. Only if the cat’s state of health deteriorates or certain risk factors are added, a visit to a veterinary clinic is indispensable.