Fever in Cats

Fever in cats – like us humans – primarily has a protective function. How do you know if your fur nose has a fever and when does it become dangerous for the cat?

Fever in Cats: Regulation and Function

If an internal body temperature of over 39 degrees Celsius is measured in a cat, either overheating (hyperthermia) or fever (pyrexia) is possible. Hyperthermia is characterized by increased production or supply of heat with simultaneous inadequate heat dissipation. Fever is characterized by a brain-controlled setpoint increase in the core body temperature, for example through infectious diseases.

Although fever is primarily unhealthy for us pet owners, the general symptom has an important immune-boosting effect and, for example, helps to combat infectious agents.

To understand how fever develops, it is advisable to take a closer look at the cat’s anatomy and physiology:

Temperature regulation in cats

The cat regulates its core body temperature through the temperature control center. This is located in a part of the diencephalon, the hypothalamus. Temperature receptors distributed on the skin receive cold or warm signals from the environment and guide them via ascending nerve pathways to the hypothalamus. The brain forwards the signals to the muscles and sweat glands via descending nerve tracts.

• Heat release: If the body registers too much heat, the brain instructs the muscles in the walls of blood vessels to relax. This then leads to peripheral vasodilation, which allows the blood to release excess heat through the skin.
• Heat production: If the cat is too cold, the opposite happens. So that less heat is given off through the skin, the vascular muscles tense and the peripheral vessels constrict. At the same time, the metabolism and the rest of the muscles are activated. This can cause the cat to shiver or chills.

What is the role of fever in cats?

In cats, the normal internal body temperature is between 38 and 39 degrees Celsius. However, if the temperature rises to higher values, there is talk of fever. Often the general symptom is considered harmful by us owners, but fever is primarily a protective function of the body.

By increasing the setpoint for the core body temperature in the brain, the activity of the immune system is improved. This is because the immune cells (e.g. scavenger cells or granulocytes) in cats can work better from a temperature of over 39 degrees Celsius.

However, above a certain level, this positive immune response comes to a standstill.

What Causes Fever in Cats?

Fever is always a reaction to negative stimuli that damage the body. In cats, the following ailments, in particular, can be:

Infectious causes:

• Bacteria: As a rule, all bacteria can lead to a fever after entering the body. Common examples are streptococci, chlamydia, or anaplasia.
• Viruses: For example Feline Immunodeficiency Virus (FIV, Cat Enaids), Feline Infectious Peritonitis (FIP), Feline Leukemia Virus (FeLV), Feline Herpesvirus-1 (FHV-1), Feline Parvo Virus (FPV, Feline Panleukopenia), Feline calicivirus
• Systemic fungal diseases (mycoses)
• Parasites: For example lungworms or toxoplasmosis

Non-infectious causes:

• Any inflammation of the tissue (e.g. of the pancreas, lungs, or liver, as well as abscesses of the skin and other organs)
• Autoimmune diseases: e.g. pemphigus foliaceus or lupus erythematosus
• Neoplasms (tumors)
• Toxins (e.g. drugs)

So while fever is an important immune reaction, hyperthermia is mainly triggered by stress or an increased ambient temperature.

Diagnosis: Can You Measure Fever in a Cat?

If the cat is noticeably calmer and shows other symptoms mentioned above, it is advisable to measure the cat’s internal body temperature.

There are two ways of doing this:

1. The internal rectal temperature can be measured using a digital clinical thermometer. You should clean and disinfect it thoroughly before use.
2. To make it more comfortable for the cat, you can apply some medicated lubricant gel, petroleum jelly, or unscented cream for sensitive skin. Since rectal insertion can still be very uncomfortable, however, you should hold the cat to protect everyone involved.

Alternatively, you can use an infrared measuring device. This measures the temperature of the cat’s ear. While this is usually easier to use, the results are not always accurate.
If the fever does not go away within a day or if the cat shows other accompanying symptoms, you should see a vet. Based on the owner survey and general clinical examination, the latter decides on further diagnostics (e.g. blood test, fecal examination, or imaging procedures).

Treatment: How to Treat Fever in Cats

Fever can be reduced symptomatically by giving so-called antipyretics (fever reducers). However, since this is not a fixed clinical picture, the veterinarian must first treat the underlying disease:

Infectious diseases: drugs such as antibiotics against bacteria, antivirals against viruses, antiparasitics against parasites, or antimycotics against fungi.
Autoimmune diseases: if necessary, administration of immunosuppressants (e.g. glucocorticoids)
Tumors: surgery, radiation, or chemotherapy

What is the Prognosis?

The prognosis of fever depends on the underlying disease and can therefore not be generalized.

Prevention: How Can Fever be Prevented?

In order to be able to protect cats from fever, more precisely from the underlying diseases, the following advice is useful:

• Eat a balanced diet.
• Many infectious diseases (e.g. cat flu, FeLV, or FIP) can be prevented with recommended vaccinations.
• To protect against bacterial infections, wounds should be cleaned and then disinfected.
• In the case of a multi-cat household, you should separate the sick cat from the healthy cats until recovery.