Fever in Cats

3 min read

Pyrexia in Cats

The normal body temperature for cats falls in the range of 99.5-102.5 Fahrenheit. Fever, referred to medically as pyrexia, can be defined as a higher than normal body temperature in cats – a body temperature of at least 103.5 ° F (39.7° C).

The cause of the fever is not always obvious, as in fever of unknown origin (FUO), which is defined as an elevated temperature on at least four occasions over a 14-day period without any obvious cause. Otherwise, fever is considered a healthy biological response to a bacterial or viral threat. The fever is a response to the threat of disease, and not the disease itself. It should be remembered that fevers can be beneficial for a sick animal, as it lowers the rapid division of bacteria and enhances the body's immune system response. However, a fever that is too high or goes on for a prolonged period of time needs medical treatment.

Symptom and Types

  • High body temperature
  • Muscle weakness
  • Decreased appetite
  • Rapid heart rate
  • Decreased body fluids/dehydration
  • Increased respiratory rate
  • Shivering
  • Shock
  • Other symptoms depending upon the underlying cause


  • Infections (most commonly, bacterial, viral, parasites, and other microorganisms)
  • Immune-mediated
  • Tumors
  • Metabolic diseases
  • Endocrine diseases
  • Miscellaneous inflammatory conditions
  • Various drugs
  • Various toxins
  • Sometimes the exact cause may not be established (e.g., in fevers of unknown origin)


Diagnosing the underlying cause may be a daunting task. You will need to provide your veterinarian with a detailed medical history for your cat, including contact with infectious agents, travel history, drug usage, insect bites, recent vaccination, allergies, surgery, and any other previous illnesses. A detailed physical examination will be conducted to identify an underlying disease condition. After the history and physical examination, routine laboratory tests will include a complete blood count, biochemistry profile, and urinalysis. These tests may provide valuable information in identifying any underlying conditions or infections that may be leading to the increased temperature. In case of infections, your veterinarian may also conduct culture and sensitivity testing to identify the specific disease causing organism so that the most suitable drugs can be prescribed to treat it. More specific testing may be required to identify the causative organism.

Radiographic studies may also help in the course of the examination, and may turn up tumors, abscesses, and/or infections. More advanced techniques like ultrasonography, echocardiography, computed tomography (CT) scan, and magnetic resonance imaging (MRI) may be employed for some patients. Other diagnostic tests, such as endoscopy, may be required in some patients if they appear to have an internal infection or obstruction.

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