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

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

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

Are Tapeworms in Cats Contagious? Vet-Reviewed Health Facts

Testing for parasites and deworming are important aspects of pet care, especially in puppies and kittens. There is a relatively high likelihood that...

How to Burrito Wrap a Cat: 7 Simple Steps

As a cat volunteer at San Francisco Animal Care and Control (ACC), I work with homeless cats usually referred to as “feral,” who...

Is Cancer Common in Cats? Our Vet Explains

Unfortunately, cats can get cancer, just like every other species, humans and animals alike. Like in people, cancer in cats is less common...

Why Is My Cat Pulling Their Hair Out? 7 Vet-Reviewed Reasons

Cats can spend up to 50% of their day grooming themselves. They do it primarily to keep themselves clean, but grooming also helps...

More related

10 Best Cat Foods for Your Sphynx Cat in 2025 – Reviews & Top Picks

The majestic Sphynx—ancient, unique, and always arriving to the party in their birthday suit. You have one of the most sought-after and alluring...

How Do Cats Say Sorry? Vet-Verified Communication & Bonding Explained

Cats don’t say sorry the same way humans do, but they might show other relationship-building behaviors. They simply don’t have the same concept...

National Hug Your Cat Day 2025: How & When It Is Celebrated

As cat parents, we feel that every day should be “Hug Your Cat Day”, but did you know that there is a specific...

The Best & Worst Fabrics for Repelling Cat Fur (With Pictures)

You love your cat, but you don’t always love their fur. Cat fur has a habit of clinging to absolutely anything and everything,...

Keep reading

Why Does My Cat Attack Me & No One Else? 7 Vet-Reviewed Reasons & What to Do

There are several reasons why your cat may choose to attack you and no one else. Oftentimes, cats, especially kittens and young adults, play rough if they haven’t been adequately socialized and find human fingers and hands to be a...

kittens training

How to Make a Cat Poop When Constipated: 10 Vet-Verified Tips

A constipated kitty is no fun. Usually, constipation is not a sign of something serious, though it can be very uncomfortable for the cat and can lead to secondary problems if it isn’t addressed. However, constipation can be a sign...

constipated cat in the litter box

Are Spider Plants Toxic to Cats? Vet Reviewed Facts & FAQ

Spider plants are a common indoor houseplant. These fern-like plants are easy to take care of and look lovely in a variety of rooms. If you have pets, however, you need to look beyond whether this plant looks nice and...

Catster_Are Spider Plants Toxic to Cats

Can Cats Eat Flies? Vet-Reviewed Facts & Health Guidelines

If you’ve ever seen a cat pounce on a fly and eat it, you may be wondering if this is safe or potentially harmful for your furry friend. So can cats eat flies? Thankfully, flies aren’t toxic or poisonous, and...

Cat hunting a fly

Why Do Cats Like the Smell of Bleach? Vet-Reviewed Feline Behavior Explanation

Cleaning with bleach may be a stellar way to kill off pesky pathogens, but the smell left behind can be a bit overwhelming. Most people don’t love the odor of bleach, but some cats can’t seem to get enough of...

Bleach Bottle Spray

How to Keep Your Cat’s Eyes Healthy: Vet-Approved Guide

A cat’s eyes are among the most beautiful features that they display, and they also happen to be among the most important. They are extremely helpful when it comes to communicating with other creatures (including humans). A cat’s eyes also...

cat with blue eyes tilts its head

How Much Attention Does a Cat Need? Vet-Reviewed Facts

While cats are often perceived as independent pets, they still require daily attention from their owners. Most cats need at least 20-30 minutes of undivided attention a day. However, the amount of attention can vary and depends on several different...

cat sleeping in owner's arms

Can Cats Eat Catfish? Vet-Approved Nutritional Facts & Advice

No, it’s not cannibalism! Cats love to eat up a fishy treat from time to time. While catfish might be named for our feline friends and have no scales, in our cats’ eyes (or tastes), it makes no difference. Fish...

Can Cats Eat Catfish