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.

What Causes Sudden Fever in Cats? Our Vet Explains Causes, Signs & FAQ

digital thermometer showing a cat has a fever

One of the most frustrating things we face as pet owners is when our furry family members don’t feel well, especially when we don’t know why. Fevers can be especially difficult to diagnose and treat because there often isn’t an external sign of the problem beyond a lethargic kitty. Let’s examine what can cause a fever in our cats and what you can do about it.

divider cats oct 2024

What Is a Fever?

A fever, at its core, is simply an elevated body temperature. It can be hard to tell if a cat has a fever simply by looking at them or touching them because their normal body temperature is higher than ours. You can expect your healthy cat’s temperature to be between 100.5 and 102.5 degrees Fahrenheit (38.1 and 39.2 degrees Celsius) 1.

A fever is a normal phenomenon where the body gets exposed to something that triggers an inflammatory response. Many pathogens can be destroyed with an elevated temperature, and your cat’s immune defenses may work better, but you can also have problems develop, ranging from lethargy to widespread blood clotting issues.

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!

Preventative wellness PGV mention keep cat healthy Preventative wellness PGV mention keep cat healthy mobile

What Causes Sudden Fever in Cats?

Unfortunately, there’s no one-size-fits-all reason for why cats develop fevers. Depending on your location, certain infections are more common than others, such as specific fungal or viral infections often cropping up in places.

Some of the major categories for causes of fevers include:
  • Bacterial infections
  • Viral infections
  • Fungal infections
  • Parasites
  • Autoimmune conditions
  • Stress or trauma
  • Vaccines

Bacterial infections may be one of the more common causes of fevers worldwide. Your cat could have a bacterial infection in their bladder or kidneys, an infected wound, or even a tooth root abscess.

Viral infections in cats may wax and wane, which means the signs come and go. They can come on quite suddenly. Feline leukemia virus (FeLV), feline infectious peritonitis (FIP), and feline immunodeficiency virus (FIV) are all important considerations in a febrile cat.

Certain parasites can trigger a fever. Fleas and ticks carry different illnesses, such as Cytauxzoonosis. While many cats are asymptomatic for Toxoplasmosis, it can cause disease in cats and people.

If your cat’s immune system starts to attack itself, it can trigger a fever. Immune-mediated anemia and thrombocytopenia can be devastating.

It’s important to note that sometimes cats will have a transient fever. Stress or trauma will sometimes elevate your cat’s temperature. For example, if your cat feels great at home and your veterinarian detects a mild fever during a physical exam, it could be nothing to worry about.

Vaccines can cause fevers. This change is normally temporary and usually goes away soon after your cat is vaccinated, but you’ll want to mention it to your veterinarian for further evaluation.

One term you might hear is “fever of unknown origin”. This condition is a fever with no readily discernible cause.

vet checking bengal cat
Image By: Pressmaster, Shutterstock

Why Does My Cat Have a Fever?

If you’re suspicious that your cat might have a fever, it’s important to look at what they may have been exposed to. Do they go outdoors, especially unsupervised? Are they on flea and tick prevention, even if they’re indoor kitties?

You’ll want to contact your veterinarian for an appointment as soon as possible or speak to your local emergency hospital about getting an exam.

divider cats oct 2024

Signs of Fever in Cats

You might touch your cat and think they feel warm, but that’s not a very good, effective way to determine a fever since cats are naturally warmer than we are. You’ll want to look for certain changes, including:

  • Decreased appetite
  • Decreased energy
  • Weakness
  • Tachypnea (elevated respiratory rate)
  • Tachycardia (elevated heart rate)
  • A delayed skin tent (gently lifting the skin on the neck and setting off it rebounds quickly when released)
  • Pale gums
  • Visible parasites
  • New swellings could be a mass, abscess, lymph nodes, or something else entirely
cat lying on the windowsill looking sick
Image Credit: Nata Aleks, Shutterstock

How Do I Care for a Cat With a Fever?

You’ll need to take your cat’s temperature to determine if your cat has a fever. While you can do this at home, having your veterinary team perform this test is often safest. The most surefire way to take a temperature is rectally with a thermometer; most cats resist that. You do not want to damage their delicate rectal tissues accidentally.

Your veterinarian will examine your cat and look for some of the signs we associate with a fever, but they will also be looking your cat over from nose to tail for any signs of abnormalities. They may focus their exam on one area where they detect something unusual. In many cases, your vet will recommend certain tests:

  • Blood work helps assess red and white blood cell changes, as well as biochemical shifts
  • Feline leukemia/FIV testing to rule out these infectious agents
  • A urinalysis helps check for evidence of a UTI or kidney infection
  • X-rays or ultrasounds can image organs for size changes, stones, fluid accumulations, and more
  • Cultures may look for bacterial infections

These tests are not all-inclusive; sometimes, your veterinarian may still be left without a concrete answer.

Treatment will depend on what your veterinarian can determine or suspect. Your veterinarian will outline supportive care, such as fluid therapy (under the skin or IV) or dietary management.

An anti-inflammatory medication may be utilized to help control your cat’s temperature. In some cases, steroids are necessary, such as autoimmune conditions. With infections, a non-steroidal anti-inflammatory drug might be used.

Antibiotics, antivirals, and antifungal medications all have their use, depending on the problem. Talk to your veterinarian about any difficulties you might face in medicating your cat. Do you need a flavored liquid compounded by a pharmacy to help you give your cat an antibiotic, or are oral medications entirely out of the question? Your vet might have an injectable option. For example, Convenia is often used as an antibiotic for certain bacterial infections in cats.

You might need to stimulate your cat to eat. You can try adding tuna water to your cat’s food. Your veterinarian might suggest a high-calorie prescription diet that is tasty and nutritious while your cat doesn’t feel well. There are also appetite stimulant medications, such as Elura.

divider cats oct 2024

Frequently Asked Questions

Is a Fever in Cats an Emergency?

Yes, a fever is considered an emergency in cats. Prolonged fevers can contribute to bone marrow suppression, blood clotting disorders, and brain swelling. Your veterinarian needs to assess your cat to help determine if there is a small problem that your cat’s body will take care of with minimal support or something requiring hospitalization and round-the-clock care.

A calico cat getting pet — might be sick or at rest.
Image Credit: krblokhin | iStock, Getty Images Plus

Can a Cat Recover from a Fever on Its Own?

In some cases, your cat’s elevated body temperature will resolve on its own. This case is especially true for transient changes such as stress. Unfortunately, other conditions need immediate medical treatment.

divider cats oct 2024

Conclusion

There are a variety of reasons for sudden fevers in cats. But no matter the reason, it can be a scary experience if you do not know what to do. If you suspect a fever, you’ll want to talk to your veterinarian as soon as possible for an exam and possible diagnostics.

Related Reads: 


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

Do Cats Hibernate? Vet-Reviewed Facts & FAQ

Cats have long captured the imagination of humans with their strange behaviors and elusive nature. From their graceful agility to their quirky expressions,...

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...

10 Ways to Train Your Kitten: Vet-Approved Tips

Cats might like us to think that they’re untrainable, but the truth is that most cats enjoy short training sessions! The best time...

Things Our Cats Hate: The Wednesday Cats of Catster

Welcome to the Wednesday Cats of Catster! Every month, we ask our cat-loving Catsters to weigh in on a new topic. This week,...

More related

Why Is My Cat Scratching the Floor? 3 Vet-Reviewed Reasons

Cats are known for their quirky behaviors, and one of them, unsurprisingly, is scratching. It’s a natural behavior that cats exhibit to mark...

10 Best Brushes for a Himalayan Cat in 2026 – Reviews & Top Picks

Himalayan cats are known for their endearing nature and stunning appearance. Caring for a Himalayan is a rewarding experience, but it requires significant...

Can Cats Eat Chocolate? Vet-Verified Facts & Safety Guide

Cats are obligate carnivores and need nothing more than quality animal protein to stay happy and healthy throughout their lives. While cats are...

How to Switch Vets: 13 Vet-Reviewed Signs It’s Time

Your pet is a vital part of your family, and no one knows them better than you—except maybe your vet. Even if you...

Keep reading

Can Cats Eat Dandelions? Vet-Approved Nutritional Benefits & FAQ

If you see your cat nibbling on common dandelions (Taraxacum officinale), it can be easy to want to rush them straight to the vet. But the truth is that dandelions are healthy for your cat in moderation. They offer numerous...

Can Cats Eat Dandelions

Why Does My Cat Bite My Ear? 10 Vet-Verified Reasons

Cats have long intrigued us with strange behaviors. One of the more unusual and often perplexing behaviors that some cats exhibit is the act of biting their owner’s ears. While cats are known for their enigmatic nature and instinctive habits,...

cat on woman's shoulder by head bite hair

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 any dog or cat will become infested with some type of internal or external parasites, be they...

tapeworm in a cat's stomach

WholeHearted Cat Food Review in 2026: Recalls, Pros & Cons

Review Summary WholeHearted pet foods was created by Petco in 2016, beginning with a line of affordable dog food, and cat foods were introduced a year later. Petco is a pet food and pet accessory company founded in the 1960s...

Wholehearted Cat Food Review

How to Stop a Cat From Spraying: 8 Vet-Approved Tips

It can be frustrating to have a cat that sprays, whether it is your cat that is spraying around the house or yard or if a stray cat is wandering onto your property and leaving the pungent smell behind. It...

black male cat spraying at the garden

Why Does My Cat Put Its Paw on My Face? 5 Vet-Verified Reasons & What It Means

As a cat lover, you may appreciate that your cat shows you attention by putting its paw on your face. Cats are strange creatures, and they do things for their own reasons, which most humans can’t even begin to understand....

cats paw on mans face

Why Does My Cat Groom Me? 9 Vet Reviewed Reasons

Felines spend a big part of each day grooming themselves—about 30–50%, in fact. So, it shouldn’t be surprising that our pets sometimes decide to groom us if we’re nearby. But why exactly do cats groom us? Is it simply because...

cat licking the nose of the woman

Can Cats Eat Raw Fish? Vet Approved Nutritional Facts & FAQ

While cats are often associated with eating fish, fish may not actually be a major part of their diets. Domestic cats descended from African wildcats, meaning their natural diets would mostly consist of small birds and mammals including small livestock...

Can Cats Eat Raw Fish

Love Cats? So Do We! Join the Catster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Catster Email Newsletter

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.