Fever in Cats

Tiffany Paul, DVM
Written by:
Published: June 7, 2022
Fever in Cats

What Is Fever of Unknown Origin in Cats?

Just like humans, cats can run a higher-than-normal body temperature when they are ill. This has many causes. A cat’s normal body temperature is between 100 F and 102.5 F.

A typical fever in a cat is considered a symptom until further diagnosis can confirm what illness is causing it. However, fever of unknown origin is a medical condition that will also need to be determined through diagnosis.

Fever in cats may be due to:

  • Excitement
  • Anxiousness
  • Pain
  • Sickness

An anxious, but otherwise healthy, cat with a 103 F temperature may not be considered feverish. On the other hand, a quiet and lethargic cat that has a 103 F temperature and shows other symptoms of illness may be considered feverish.

A veterinarian usually interprets your cat’s body temperature by:

  • Performing a thorough physical exam
  • Examining your cat’s medical history

Symptoms of Fever of Unknown Origin in Cats

When your cat has a fever, they may:

  • Feel lethargic
  • Sleep more than usual
  • Have no appetite
  • Hide
  • Avoid normally enjoyed activities
  • Vomit
  • Have diarrhea

If any of these symptoms occur, you should call your veterinarian for an appointment.

Causes of Fever of Unknown Origin in Cats

Persistent fevers that last more than a day may be caused by infection, inflammation, and pain.

You may suspect a fever if your cat feels warmer to the touch than usual. This can be confirmed at home with a rectal or ear thermometer.

Some fevers in cats have clearly identifiable causes which include:

  • Upper respiratory tract infection
  • Severe dental infection

Other fevers, however, are not easily explained. When your cat does not have any symptoms other than a fever and general malaise, your veterinarian may simply diagnose them as having a fever of unknown origin.

How Veterinarians Diagnose Fever of Unknown Origin in Cats

Your veterinarian will first look at your cat’s medical history and will ask you to list your cat’s symptoms and give details about their behavior.

Next, your veterinarian will physically examine your cat. This will include a temperature reading using a rectal or ear thermometer. They may also look for wounds or areas of pain.

Sometimes, a physical exam may not show a reason for your cat’s fever, and further procedures and lab tests may be needed, such as:

  • Blood test for Feline Leukemia Virus (FeLV)
  • Blood test for Feline Immunodeficiency Virus (FIV)
  • Complete blood count for infection or inflammation
  • Biochemistry panel for abnormal organ function
  • Urinalysis for urinary tract infection
  • Ultrasound of the abdomen

Your veterinarian may also take an x-ray to show:

  • Reasons for your cat’s pain upon physical examination
  • Pneumonia
  • Bowel blockage due to something your cat ate

Treatment of Fever of Unknown Origin in Cats

If a specific cause for the fever is found, treatment will address the cause and symptoms of the fever. Treatment of fever may include:

  • IV fluids, which also treat secondary dehydration
  • NSAIDs
  • Antibiotics

If your cat is running a very high fever or is not eating and drinking, they may have to be hospitalized overnight.

Recovery and Management of Fever of Unknown Origin in Cats

Most cats respond well to treatment and will recover from a fever within 1 to 5 days.

Fever of Unknown Origin in Cats FAQs

What can cause a fever of unknown origin in cats?

Cats can have a fever for a variety of reasons such as illness, anxiety, or pain. A veterinarian will ask about your cat’s medical history, perform a physical examination, and may recommend further testing to diagnose the cause of the fever.

How long do cat fevers last?

Fevers in cats can last an average of 1-5 days depending on the cause and severity of illness.

Can parasites cause fevers in cats?

In general, parasites do not cause fevers in cats. However, parasites may weaken a cat’s immune system and make them more susceptible to secondary fungal, bacterial, or viral infections that usually cause a fever.

Do cats recover from fevers?

Yes, a fever in cats is usually a temporary sign of illness or pain. Your veterinarian will determine the cause of the fever and will likely treat it with fluids, anti-inflammatories, or antibiotics.

Featured Image: iStock.com/charliepix


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