How to Tell if a Cat Has a Fever + Vet Q&A

Cat’s normal body temperature ranges around 100.5-102.5°F, a fever is considered to be present when a cat’s body temperature rises above 103°F. 

When a cat is sick, and especially when they are senior cats, their body often mounts an immune response to fight off infection, inflammation, and disease. 

As part of this response, the cat’s body releases certain chemicals that can affect blood flow and increase body temperature.
To answer the commonly asked question we get ” How to tell if a cat has a fever ” We created this guide of symptoms and signs, and we included chapters on how to measure a cat’s fever and its causes.

Let’s scratch this topic 🙂

how to tell if a cat has a fever

Behavioral Changes

One of the primary indicators that your cat may have a fever is a change in their behavior. 

Cats with a fever may become uninterested in playtime, and less likely to seek out affection. 

Your cat may also appear more irritable or temperamental than usual, demonstrating a decreased level of tolerance for any type of activity.

Other Important symptoms include:

  • Poor grooming
  • Lethargy
  • Loss of appetite
  • Hiding

Poor grooming

Cats may experience muscle aches, joint pain, and overall discomfort due to the elevated body temperature associated with fever. 

When a cat is unwell and dealing with a fever, it may prioritize resting and conserving energy over grooming activities.


Lethargy is defined as a state of decreased energy and activity level, often accompanied by a lack of enthusiasm or interest. 

A cat with a fever will have other accompanying symptoms along with lethargy. These symptoms may include loss of appetite, increased thirst, vomiting, diarrhea, weakness, respiratory issues, or changes in sleeping patterns

Loss of appetite

Fever triggers physiological changes in the body, including an increase in metabolic rate and energy expenditure as the immune system works to fight off the underlying cause of the fever. 

These changes can affect a cat’s desire to eat, leading to a reduced appetite. The cat may exhibit a lack of interest in food, eat smaller portions, or refuse to eat altogether.

To fight off the problem, a heightened immune response can cause discomfort, lethargy, weakness, and other systemic symptoms in addition to the loss of appetite.


Cats have retained many of their wild instincts, and one of them is seeking isolation when they are not feeling well. In the wild, showing signs of illness or weakness can make them vulnerable to predators. 

Hiding allows them to find a quiet and secure place where they can rest undisturbed.

Reasons why cat with fever hides:

  • Discomfort and Rest: When cats have a fever, they may experience discomfort, fatigue, and lack of appetite. Hiding provides them with a quiet environment where they can rest and conserve their energy. It allows them to recover without unnecessary stimulation.
  • Temperature Regulation: Cats may seek out cool or warm places to regulate their body temperature when they have a fever. Hiding in certain areas of the house can provide them with a more suitable environment to manage their body temperature and alleviate discomfort.
  • Stress Reduction: Cats may naturally perceive illness or discomfort as a stressor, and hiding can be a coping mechanism to reduce stress. By finding a secluded spot, they can feel more secure and minimize external stimuli that may exacerbate their stress response.

Physical Symptoms

Physical signs of fever:

  • Warm ears
  • Dry nose
  • Glassy eyes

Warm ears

Cats’ ears play a role in regulating their body temperature. 

The ears are not protected by fat or fur so when a cat is exposed to a warm environment or has an elevated body temperature, the blood vessels in their ears dilate to release heat. 

If your can wasn’t sleeping or been outside in hot weather, the ears may feel warm to the touch and a sign of fever.

In combination with other symptoms from the list, warm ears in cats are a symptom of fever. 

Dry nose

A cat’s nose can naturally vary between wet and dry throughout the day, and it can be influenced by external factors such as heat sources or sun exposure. 

However, if a cat’s nose is consistently warm or excessively dry, it could potentially be a sign of an underlying health issue, including fever.

Glassy eyes 

When a cat has a fever, their body temperature is elevated, and this can lead to inflammation or discomfort in the eyes, causing excessive tearing and a glassy appearance.

Glassy eyes can also be a sign of other eye problems such as:

  • Conjunctivitis –  red, inflamed eyes, 
  • Cataracts –  glassy appearance due to opacities in the lens of the eye

Medical symptoms 

If physical and behavioral signs are causing medical symptoms, it is time for a vet visit. 

If you notice:

  • Rapid heart rate
  • Dehydration
  • Vomiting
  • Diarrhea
  • Respiratory issues

Your cat needs a physical checkup to determine the underlying cause of exhibited symptoms.  

Rapid heart rate

Tachycardia is the medical term used to describe a heart rate that is faster than normal. 

In cats, a heart rate greater than 220 beats per minute (bpm) is considered rapid.


Dehydration occurs when a cat loses more fluids than it takes in, resulting in an imbalance in the body’s water content. 

Fever can contribute to dehydration in several ways:

  • Increased water loss: Fever causes the cat to lose additional fluids through panting and increased respiratory rate, leading to higher water loss from the respiratory tract.
  • Decreased water intake: Cats with fever often experience reduced appetite and may drink less water than usual, further exacerbating the risk of dehydration.
  • Altered fluid balance: Fever can disrupt the body’s fluid balance and lead to electrolyte imbalances, such as sodium, potassium, and chloride, which are essential for maintaining proper hydration.

To recognize dehydration in cats pay attention to: 

  • dullness, 
  • weakness, 
  • lack of appetite, 
  • sunken eyes, 
  • dry and tacky gums, 
  • decreased urine output

Vomiting and/or Diarrhea

Fever is often a symptom of infectious diseases, such as viral or bacterial infections, which can affect the gastrointestinal tract and lead to vomiting and diarrhea.

Some viral infections, like feline panleukopenia virus, feline calicivirus, and feline herpesvirus, can cause vomiting and diarrhea in cats.

Respiratory issues

Cats with fever may be more susceptible to upper respiratory infections, such as viral or bacterial infections. These infections can affect the nose, throat, and sinuses, leading to symptoms like sneezing, coughing, nasal discharge, and congestion.

Cats with pre-existing respiratory conditions, such as asthma or chronic bronchitis, may experience worsening symptoms during a fever. 

The elevated body temperature can trigger inflammation and constriction of the airways, making it harder for the cat to breathe].

In some cases, fever in cats can be a sign of an underlying respiratory infection, such as pneumonia. 

Pneumonia is an inflammation of the lungs often caused by bacterial or viral agents. Fever can accompany pneumonia, along with symptoms like coughing, difficulty breathing, lethargy, and loss of appetite.

How to Check a Cat’s Temperature Without a Thermometer

  1. Feel the ears: Gently touch your cat’s ears to see if they feel unusually warm or hot.
  2. Check the paw pads: The paw pads of a feverish cat may also feel warmer than usual.
  3. Observe behavior: Monitor for signs of discomfort, excessive panting, or seeking cool surfaces, which may indicate a fever.

How to Take Your Cat’s Temperature with a Thermometer

It is best left to your vet but if you decide to measure your cat’s temperature please choose a thermometer made for animals. 

Human thermometers are not suitable for cats, as they have thinner and more delicate rectal tissues. 

Digital thermometers are both accurate and easy to use, making them an excellent choice for pet owners.

When selecting a thermometer, look for one that has a flexible tip, as this will be more comfortable for your cat. 

Avoid glass thermometers, as they can break and cause injury.

Proper Technique for Taking a Cat’s Temperature

Before taking your cat’s temperature, ensure that they are calm and relaxed. It’s a good idea to have a helper hold your cat still while you take their temperature. 

  1. Locate the rectal area, and clean the area with a damp cloth or baby wipe. 
  2. Lubricate the thermometer with petroleum jelly or a similar product, and insert the thermometer approximately one inch into the rectum. 
  3. Hold the thermometer for a full minute, then remove it and read the result.

Be gentle when inserting the thermometer to avoid causing any discomfort to your cat. 

If your cat becomes agitated or distressed, stop the procedure and try again later.

how to measure cats fever

Understanding the Results

A normal cat temperature should range between 100.5°F and 102.5°F. If your cat’s temperature falls outside of this range, it may be an indication of illness or injury. 

Temperature checks should be a part of regular cat care, especially when a cat reaches senior age.

A temperature reading above 103°F is considered a fever.

When to Seek Veterinary Care

If your cat is showing symptoms of a fever, it’s always better to consult a veterinarian early. 

  1. If your cat has a body temperature above 104°F, seek veterinary care immediately; fevers can lead to dehydration and other serious complications.
  1. If a cat’s fever does not dissipate after a few hours or persists for several days.
  2. If a fever recurs.
  3. If a cat with a fever exhibits additional symptoms such as severe lethargy, seizures, or vomiting, it’s critical to seek immediate veterinary care. These symptoms may indicate more severe underlying issue or illness that needs to be treated promptly.

What causes fever in cats

Fever in cats, also known as pyrexia, can be caused by:

Infections: Fever in cats can be a response to bacterial, viral, or fungal infections. 

Common infectious causes include: 

  • localized or systemic infections,
  • bacterial endocarditis, 
  • toxoplasmosis, 
  • Lyme disease, 
  • psittacosis, 
  • ehrlichiosis, 
  • feline leukemia, 
  • babesiosis, 
  • brucellosis, 
  • aspergillosis, 
  • urogenital infections.

Inflammatory conditions: Inflammatory diseases such as rheumatoid arthritis. 

Immune-mediated diseases

Cancer: Some types of cancer, including lymphoma and other malignancies, can cause fever in cats.

Trauma or injury: Cats may develop a fever in response to trauma, such as bite wounds, lacerations, or puncture wounds.

Metabolic disorders: thyroid disorders, liver disease, or kidney disease.

Less common causes of fever in cats:

A bobcat fever in cats/Cytauxzoonosis – A tick-borne condition 

Haemobartonellosis – A parasitic bacterial blood infection seen in cats.

Ehrlichiosis – Also a tick-borne condition that can affect cats.

Bartonellosis – More commonly known as cat scratch fever.

Toxoplasmosis – A parasitic condition known to cause fever in cats.

cat scratch fever

What To Do If Your Cat Has a Fever

  1. Take your cat to the vet for diagnosis and treatment. Do not give human medication to cats because they are toxic to cats. Treatment for fever in cats depends on the underlying cause. If an infection causes the fever, your veterinarian may prescribe antibiotics or antiviral medications. If the fever is caused by an autoimmune disorder or cancer, your veterinarian may recommend immunosuppressive therapy or chemotherapy. 
  1. Encourage your cat to drink water. 
  2. Monitor your cat’s temperature regularly as directed by your veterinarian to track their progress.
  3. Create a quiet and comfortable environment for your cat to rest and recover, away from excessive noise or stressors.

Vet Q$A

1. Can a cat’s fever go away on its own?

Yes, a cat’s fever can potentially go away on its own if it is caused by a mild infection or a temporary condition. However, it is always recommended to consult with a veterinarian to determine the underlying cause and provide appropriate care.

2. Should I give my cat fever-reducing medication at home?

It is not advisable to administer any medication to your cat without veterinary supervision.