# Fever in Cats: Causes, Temperature, and Symptoms A fever in cats means the body's thermostat has been reset to a higher temperature, usually because of infection, inflammation, immune disease, or cancer [1]. In cats, infections are the most common cause of fever [1]. Knowing what a real fever looks like, how to measure it, and which signs mean an emergency helps you act quickly. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - A cat's normal body temperature is roughly 100.5 to 102.5°F (38.1 to 39.2°C). Anything at or above 103°F (39.4°C) is generally considered a fever. - Fever is not a disease. It is a sign that the hypothalamus, the brain's thermostat, has been reset higher [1]. - Infections are the most common cause of fever in cats [1]. - A cat with a fever often hides, stops eating, feels warm to the touch, and breathes faster than usual. - Never give a cat human fever medicine. Acetaminophen and ibuprofen are toxic to cats, and a veterinarian must calculate any safe dose from your cat's weight and health. ## What a Fever in Cats Looks Like and What Is Normal ### Normal Cat Temperature A healthy cat runs warmer than a person. Normal rectal temperature in cats is about 100.5 to 102.5°F, which is 38.1 to 39.2°C. A mild elevation can happen from stress, a hot room, or a recent romp, so one high reading is not proof of illness. ### Fever in Cats Temperature: Celsius and Fahrenheit Owners often ask about fever in cats celsius because many thermometers and veterinary charts use Celsius. A rectal temperature of 103°F (39.4°C) or higher is the usual cutoff for fever. Temperatures above 104°F (40°C) are more concerning, and anything at or above 105°F (40.5°C) is an emergency. ### Fever in Cats Symptoms The signs are often subtle. Watch for: - Hiding, sleeping more, or acting withdrawn - Not eating or drinking - Warm ears, paws, or belly - Fast breathing or panting - Shivering, even in a warm room - Low energy, weakness, or reluctance to move - Vomiting, diarrhea, or a poor coat A cat with a fever may also show signs that point to a specific problem. Ear pain or head shaking can suggest an ear infection, which you can read about in [Ear Infections In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infections-in-cats-symptoms) or [Symptoms Of Cat Ear Infection](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-cat-ear-infection). Sneezing, eye discharge, and nasal congestion point toward an upper respiratory problem, covered in [Upper Respiratory Infection In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/upper-respiratory-infection-in-cats-symptoms). Straining to urinate or crying in the litter box can mean a bladder issue, described in [Symptoms Of Bladder Infection In Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-bladder-infection-in-cats) and [What Are Symptoms Of A Uti In A Cat](/knowledge/veterinary-medicine/symptom-guides/what-are-symptoms-of-a-uti-in-a-cat). ### How to Measure a Cat's Temperature The most accurate method at home is a digital rectal thermometer. Use a pet-safe or human digital thermometer, apply a water-based lubricant, and insert it about one inch into the rectum. Hold it in place until it beeps. Ear thermometers are less reliable in cats because ear shape and debris affect the reading. If you are not comfortable, do not force it. A veterinarian can measure it safely. ## What Causes Cat Fever Fever happens when the hypothalamus resets the body's target temperature upward [1]. That reset can come from many triggers. In both animals and people, fever may indicate infection, inflammation, an immune-mediated disease, or cancer [1]. In cats, infections are the most common cause [1]. ### Fever in Cats Causes: Common Versus Serious | Cause | Typical clues | How urgent | |---|---|---| | Viral infection (upper respiratory, calicivirus, herpesvirus) | Sneezing, eye or nose discharge, mouth ulcers, drooling | See a vet within 24 hours if not eating | | Bacterial infection (abscess, bite wound, dental, urinary) | Swelling, pus, bad breath, straining to urinate, pain | Same day | | Tick-borne disease (relapsing fever, other tick illnesses) | Fever that comes and goes, weakness, sometimes tremors or seizures | Emergency if neurologic signs appear | | Cat-scratch disease (Bartonella) | Fever after a scratch or bite, swollen lymph nodes, sometimes confusion or seizures in people | Same day for the cat, and see a doctor for any person who was scratched | | Q fever (Coxiella burnetii) | Rare in cats, linked to contact with a cat that recently gave birth | Contact your vet and your physician if a person is ill | | Severe fever with thrombocytopenia syndrome (SFTS) | Tick exposure, fever, low platelets, bleeding, sudden collapse | Emergency | | Immune-mediated disease | Recurring fever, joint pain, lameness, no clear infection | Same day to 48 hours | | Cancer | Weight loss, poor appetite, lump, ongoing fever | Routine to same day, depending on severity | | Fever of unknown origin | Fever that keeps coming back with no clear cause after testing | Ongoing veterinary workup | Some of these causes are zoonotic, meaning they can pass between cats and people. A rare human case of Q fever was linked to a domestic cat, and the cat that had recently given birth tested positive for the bacteria [2]. Tick-borne relapsing fever caused by Borrelia persica has been reported in a cat, which developed head tremors and generalized seizures within eight hours of the first neurologic signs [3]. Cat-scratch disease from Bartonella henselae can cause high fever and neuropsychiatric symptoms in people, sometimes months after a scratch [4]. Severe fever with thrombocytopenia syndrome virus has spread from a dog to two owners and a cohabiting cat in one household, and the cat died two weeks after the dog [5]. These are uncommon, but they show why a fever plus a tick, a scratch, or a sick pet in the home deserves prompt attention. ### Fever in Cats Meaning Fever in cats meaning is simple: the body is fighting something or reacting to something. It is a signal, not a diagnosis. The pattern matters. A fever that spikes and falls, a fever that never breaks, and a fever with neurologic signs each point to different problems. ## Red Flags That Make It an Emergency Go to an emergency clinic now if your cat has any of these: - Temperature at or above 105°F (40.5°C) - Seizures, tremors, head pressing, or sudden blindness - Trouble breathing, open-mouth breathing, or blue gums - Collapse, extreme weakness, or inability to stand - Repeated vomiting or bloody diarrhea - Straining to urinate with no urine produced, especially in a male cat - A fever with bleeding, bruising, or tiny red spots on the gums - A fever after a tick bite or after a fight with another animal Call your veterinarian the same day for a fever between 103°F and 104.9°F, a cat that has not eaten for 24 hours, or a fever that returns after seeming to improve. ## Safe Things You Can Do at Home While Waiting You cannot treat a cat's fever at home with medicine. What you can do is keep your cat comfortable and gather information for your veterinarian. - Offer water in several spots. Dehydration makes fever worse. - Offer small amounts of a bland, familiar food. Do not force-feed. - Keep your cat in a quiet, cool room away from other pets and children. - Do not wrap your cat in blankets or apply ice. Cooling too fast can cause shivering, which raises temperature. - Never give acetaminophen, ibuprofen, aspirin, or any human fever reducer. These can be fatal to cats. - Write down the temperature, the time, and any symptoms so your vet has a clear timeline. - If another pet or a person in the home is also sick, tell your veterinarian. Household clusters of illness can point to a shared source [5]. ## What Your Veterinarian Will Check and Test Your veterinarian will start with a full physical examination and a rectal temperature. They will ask about appetite, water intake, litter box habits, travel, ticks, other pets, and any scratches or bites. Testing often includes: - Complete blood count and chemistry panel to look for infection, inflammation, and organ changes - Urinalysis and urine culture - Feces testing for parasites - Tick-borne disease testing if there is tick exposure - Bartonella testing if there is a scratch or bite history - Imaging such as X-rays or ultrasound if the exam points to a specific organ - PCR or other specific tests when a rare infection is suspected Determining the cause of a fever requires a history, physical examination, and sometimes laboratory or other diagnostic tests [1]. Often, a fever resolves on its own or in response to antibiotic therapy [1]. In a small percentage of animals, the fever continues or keeps coming back and the cause cannot be determined, which is called fever of unknown origin [1]. Treatment depends on the cause. Antibiotics are used for bacterial infections. Supportive care includes fluids, nutrition, and sometimes anti-nausea medication. Any medication dose is calculated by your veterinarian from your cat's weight and health, so never guess at a dose at home. ## Prevention and Monitoring You cannot prevent every fever, but you can lower the odds and catch problems early. - Keep your cat indoors or supervise outdoor time to reduce ticks, fights, and contact with sick animals. - Use veterinarian-approved flea and tick prevention year round. - Check your cat's skin and ears after any time outdoors. - Keep up with wellness visits and vaccines. - Isolate a new cat for two weeks before introducing it to resident pets. - Watch for changes in appetite, water intake, and litter box use. These are often the first signs. - If you have a pregnant cat, take extra care with hygiene. Q fever has been linked to a parturient cat in a rare human case [2]. - If a person in the home develops a fever after contact with a sick cat, they should see a physician and mention the cat exposure. ## Limitations and When to Contact a Veterinarian This article cannot tell you what is causing your cat's fever. Only a veterinarian who examines your cat can do that. Individual cases need a veterinarian. Contact your veterinarian the same day if your cat has a fever between 103°F and 104.9°F, has stopped eating, is vomiting, or seems painful. Go to an emergency clinic now if the temperature is 105°F (40.5°C) or higher, if your cat is having seizures or tremors, if breathing is labored, if your cat collapses, or if you see bleeding or bruising. Schedule a routine visit if your cat had a fever that resolved but the cause was never found, or if fevers keep returning. A fever of unknown origin needs an ongoing workup [1]. ## Frequently Asked Questions ### What temperature is a fever in a cat? A rectal temperature of 103°F (39.4°C) or higher is generally considered a fever in cats. Normal is about 100.5 to 102.5°F (38.1 to 39.2°C). A reading above 105°F (40.5°C) is an emergency. ### What causes fever in cats most often? Infections are the most common cause of fever in cats [1]. Other causes include inflammation, immune-mediated disease, and cancer [1]. Your veterinarian will use history, examination, and testing to narrow it down. ### Can I give my cat human fever medicine? No. Never give a cat acetaminophen, ibuprofen, or aspirin. These are toxic to cats and can be fatal. Only a veterinarian can decide on a safe medication and calculate the dose from your cat's weight and health. ### How do I take my cat's temperature at home? Use a digital rectal thermometer with a water-based lubricant, insert about one inch, and hold until it beeps. Ear thermometers are less reliable in cats. If your cat struggles, stop and let a veterinarian do it. ### When should I worry about a fever in my cat? Worry right away if the temperature is 105°F (40.5°C) or higher, or if your cat has seizures, tremors, trouble breathing, collapse, or bleeding. Call the same day for a fever between 103°F and 104.9°F or a cat that has stopped eating. ## Related Articles - [Ear Infections In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/ear-infections-in-cats-symptoms) - [Upper Respiratory Infection In Cats Symptoms](/knowledge/veterinary-medicine/symptom-guides/upper-respiratory-infection-in-cats-symptoms) - [Symptoms Of Cat Ear Infection](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-cat-ear-infection) - [Symptoms Of Bladder Infection In Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-bladder-infection-in-cats) - [What Are Symptoms Of A Uti In A Cat](/knowledge/veterinary-medicine/symptom-guides/what-are-symptoms-of-a-uti-in-a-cat) - [Symptoms Of Urinary Infection Cats](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-urinary-infection-cats) - [How to Tell If Your Cat or Kitten Has a Fever](/knowledge/veterinary-medicine/symptom-guides/how-to-tell-cat-fever) - [Fever in Cats: Treatment and Safe Home Care](/knowledge/veterinary-medicine/symptom-guides/fever-in-cats-treatment-home-care) - [My Kitten Feels Warm: Normal or a Fever?](/knowledge/veterinary-medicine/symptom-guides/kitten-feels-warm-fever) - [Cytauxzoon felis Bobcat Fever in Cats: Pathogenesis, Diagnosis, and Critical Care Management](/knowledge/parasites/pet-parasites/cytauxzoon-felis-cats-bobcat-fever-severe-mortality-diagnosis) ## References 1. [Fever of Unknown Origin in Cats - Cat Owners](https://www.merckvetmanual.com/cat-owners/metabolic-disorders-of-cats/fever-of-unknown-origin-in-cats). Merck Veterinary Manual. 2. [A human case of Q fever associated with cat in China: a neglected risk factor of Q fever](https://pubmed.ncbi.nlm.nih.gov/41645351/). One health outlook, 2026. 3. [Neurological manifestations in a cat with tick-borne relapsing fever caused by Borrelia persica](https://pubmed.ncbi.nlm.nih.gov/41985201/). Research in veterinary science, 2026. 4. [Atypical cat-scratch disease with acute high-grade fever and neuropsychiatric symptoms: a case report](https://pubmed.ncbi.nlm.nih.gov/42581991/). Frontiers in veterinary science, 2026. 5. [Transmission of severe fever with thrombocytopenia syndrome virus from a dog to humans and a cat in a household cluster](https://pubmed.ncbi.nlm.nih.gov/42183047/). One health (Amsterdam, Netherlands), 2026. ## Further Reading - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)