Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Why Does My Cat Have a Fever? 5 Vet-Reviewed Common Causes

digital thermometer showing a cat has a fever

Cats normally have temperatures between 100º F and 102.5º F; anything above that is considered to be a fever, also known as pyrexia. Fevers play an essential role in keeping cats healthy as they trigger their immune systems to shift into high gear and make it difficult for viruses and bacteria to proliferate.

Fever can be caused by parasites, trauma, and infections; anything that triggers an inflammatory response. Cats with fevers often show other signs of illness, such as a lack of energy and interest in eating and drinking. Cats feeling feverish also sometimes shiver, hide, and show little interest in activities such as grooming themselves.

It’s not always easy to tell if your cat has a fever, as their body temperature is higher than ours, but if their ears feel quite warm, especially if the outside temperature isn’t hot, this can be a sign that your cat has a fever. If you think your cat has a fever that lasts more than 24 hours, or if they also seem unwell, it is time to make an appointment with your vet. They will be able to examine your cat and run tests to find out what is causing the fever, and get them the right treatment.

divider cat paws oct 2024

The 5 Common Causes Why Cat’s Have Fever

1. Parasites

Cats can be infected by various parasites, but the two most likely to cause fevers are toxoplasmosis and cytauxzoonosis. Cats infected with toxoplasmosis rarely show signs of infection, but when they do, they typically include a lack of interest in eating, weight loss, and fever. Some may develop jaundice and difficulty breathing. Treatment usually involves antibiotics, and cats who recover generally do just fine.

Cytauxzoonosis is a tick-borne disease, caused by a protozoa that results in widespread inflammation and organ and tissue damage. Infections are commonly seen when ticks are at their busiest, generally between April and September. Signs of cytauxzoonosis infections include lack of interest in eating, vomiting, weakness, and jaundice. Most cats suffering from cytauxzoonosis infections have extremely high fevers.

Fast intervention is essential with cytauxzoonosis, and cats must spend a few days in the hospital to get back on their feet. The treatment usually involves antiprotozoal medication and supportive care.

sick cat lying on the floor
Image Credit: Oporty786, Shutterstock

2. Cancer

Several types of cancer can cause cats to develop fevers, but lymphoma tends to be the type that impacts the most felines. Other cancers that are commonly found in cats include soft-tissue sarcomas and squamous cell carcinomas.

Regular medical checkups ensure that severe medical conditions (such as cancer) are diagnosed as quickly as possible, which can lead to better outcomes over time.


3. Infections

Bacterial, fungal, and viral infections can all cause fevers in cats. Although the types of infections that lead to fevers can occur anywhere in a cat’s body, viral infections that affect the upper respiratory tract are particularly common; feline calicivirus and feline herpes virus are frequently encountered, culprits.

Feline leukemia virus, feline immunodeficiency virus (FIV), and feline coronavirus (also known as feline infectious peritonitis, or FIP) are relatively common viruses in the cat population, and can all present with fever and lethargy.

Cats that get into fights can end up with infections that often turn into abscesses, a pocket of pus under the skin. Fever, lethargy, and pain are usually the first signs of an abscess brewing. Feline lower urinary tract disease, including infection, are also common causes of inflammation and fever in cats.

Antibiotics are prescribed to help cats suffering from bacterial infections get back on their feet. Some viral infections respond well to supportive care, while others can have lifelong effects, or be fatal.

If you suspect your cat has an infection, we advise you to speak to a vet.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money


4. Brain Trauma

Brain injuries can cause problems with temperature regulation, which can lead some cats to spike fevers or have abnormally low body temperatures. There are two steps involved when cats experience brain trauma; there’s the initial injury and then the problems that crop up as a result.

Common secondary brain injuries include bleeding blood vessels and severe tissue swelling. Other signs of brain trauma include pupils of different sizes and a particularly slow heart rate. Brain trauma can be caused by something sudden, like being hit by a car, but long-term health problems such as high blood pressure, blood clotting disorders, and heart attacks can also cause problems.


5. Heat Exhaustion and Stroke

Heat exhaustion and stroke are caused when cats are exposed to hot, humid temperatures for too long, and are unable to cool down. Outdoor cats are more commonly affected, but indoor cats are also susceptible, with sunny spots and indoor heating.

Overweight pets, kittens, brachycephalic cats (eg. Persians), and those with conditions such as diabetes, kidney disease, and heart problems, are also more at risk. Heat exhaustion is diagnosed when cats’ temperatures reach between 103º F and 104º F. Signs to look out for include diarrhea, vomiting, rapid breathing, and seizures.

sick cat lying on blanket
Image credit: one photo, Shutterstock

divider cat faces oct 2024

Frequent Asked Questions

Are Fevers Always Caused by an Illness?

No. Benign activities, including exercise and excitement, can cause cats’ temperatures to be a bit higher than normal.

Are There Other Potential Causes of Elevated Temperatures in Cats?

Yes. Some types of medication can cause cats to have temperatures, as can various inflammatory conditions.

a sick siberian cat being carried by owner
Image Credit: Anna Krivitskaya

How Do Veterinarians Determine What’s Causing a Cat’s Fever?

Veterinarians rely on information provided by pet parents to get started. Tests for feline leukemia virus and feline immunodeficiency virus are frequently part of the workup. Urinalysis and fecal tests are commonly ordered, and imaging studies, such as ultrasounds and X-rays, are also used.

divider cat paw scratch oct 2024

Conclusion

Fevers are commonly seen in cats who aren’t feeling well. They actually play an important role in the immune function since they help cats fight infection. A temperature between 100º F and 102.5º F is considered normal for cats. While many fevers go away with supportive care, pets who don’t start feeling better relatively quickly should receive a thorough veterinary evaluation, and those with high fevers should receive immediate medical attention.

Fevers can have several causes, including infections, trauma, parasites, and cancer, and getting cats back on their feet involves identifying the cause of the problem and providing the appropriate treatment.


Featured Image Credit: Evgeniy Kalinovskiy, Shutterstock

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Neurological Disorders in Cats: Our Vet Explains Signs, Causes & Treatments

It’s really scary when our pets become ill, particularly when they’re not acting like their normal selves. Often, one of the first signs...

Two veterinarians holding down a Persian cat at the exam table

Why Is My Cat Lethargic & Limping After a Vaccine? Vet-Verified Facts

Most cats are not big fans of visiting the vet, so you can imagine how unimpressed they will be when they have to...

cat lying on bed at home

Toxoplasmosis Symptoms in Cats: Our Vet Explains the Causes, Signs & Treatments

Toxoplasmosis is a disease impacting cats that can be picked up from the environment. Toxoplasmosis is commonly discussed in households due to the...

Female vet holding a sick cat close-up

Cat Glaucoma: Signs, Causes, Diagnosis, Care & FAQ (Vet Answer)

Cats are capable of developing glaucoma, just as humans do. Glaucoma is a medical condition seen when high pressure builds up inside the...

acute glaucoma in adult cat's eyes

More related

owner collecting urine of cat

Why Is My Cat Peeing Blood? Our Vet Explains Causes, Treatments & FAQ

Imagine going to clean out your cat’s litter box and suddenly witnessing your cat urinating out what appears to be blood! As an...

tabby cat on the sofa

Megaesophagus in Cats: Signs, Causes & Treatments (Vet Answer)

We all know just how important the esophagus is to not just the human body but to the bodies of our pets as...

vet holding burma cat

Focal Seizures in Cats: Our Vet Explains Signs, Causes & Care Tips

Seizures can be a frightening experience for both owners and their cats. There are many different types and causes. Usually, seizures are not...

a stray cat outdoors with keratitis

Keratitis in Cats: Causes, Diagnosis & Treatments (Vet Answer)

If you notice your cat squinting or has a discolored spot on the surface of their eye, take them directly to their veterinarian....

Keep reading

What Can Cats Drink Besides Water? 3 Vet-Approved Options

Did you know your cat probably doesn’t drink enough water? Urinary problems are the reason behind many vet visits, whether it’s treatment for bladder stones, cysts, or other problems falling under Urinary Tract Disease. Urinary problems are actually the leading...

What Can Cats Drink Besides Water

8 Best Cat Foods to Prevent Vomiting in 2025 – Reviews & Top Picks

One of the most frustrating things for a cat owner is when their cat is frequently vomiting. It will often be something simple like a hairball or a recent change in food and should pass quickly, but if it turns...

tabby cat eating from metal bowl

6 Best Cat Foods for Outdoor Cats in 2025 – Reviews & Top Picks

People love to joke that cats domesticated us and not the other way around, owing to their exceptionally independent nature. In fact, even though we have been companions for over 4,000 years, research shows that about 50% of these small...

hungry Nebelung cat with kibbles in front

Do Cats Get Winter Coats? Vet-Verified Fur Facts & Care Tips

The trees turning colors and the weather growing colder aren’t the only changes that happen during the fall months. Like many dogs, cats also get winter coats. This fur coat is thicker and denser than their summer coat and serves...

black long-haired cat winter snow

How to Tell if Cat Mating Was Successful: 9 Signs to Look For

If you have an unspayed female cat, she can become pregnant very easily. Your cat’s estrus cycle shares some similarities to a human’s menstrual cycle. Your unspayed female can go into heat by 6 months of age or even earlier,...

Pregnant White Cat

Are Baby Wipes Safe to Use on Cats? Vet-Reviewed Facts & FAQ

For the most part, cats are rather self-reliant creatures. They do a majority of their bathing and grooming and only occasional input from you is necessary. But there are times when felines need a little additional help to stay entirely...

Catster_Are Baby Wipes Safe for Cats

7 Best Top-Entry Litter Boxes in 2025 – Reviews & Top Picks

Top-entry litter boxes are aesthetically pleasing and fit in with modern décor more than standard litter trays. They’re tall and hygienic and help keep your house clean from lumps of kitty litter stuck to your feline’s paws. These litter boxes...

ginger cat inside red grey enclosed litter box

Play Aggression in Cats: Vet-Approved Signs, Causes & Solution

It’s all fun and games with your kitty until the claws are out or they are causing mischief! All too often, we can be having a cuddle or fun time with our cat when our forearm is suddenly gripped by...

Aggressive cat growling