Fever in Cats: Causes and Management

1 Fever vs. Hyperthermia

Fever is an abnormal rise in body temperature caused by a change in the hypothalamic temperature set point; by strengthening phagocytosis, interferon release, and lymphocyte transformation it plays a positive role in defending against infection. Hyperthermia, by contrast, is a rise in temperature from heat that cannot be dissipated, increased muscle activity, or faster metabolism, without any change in the set point.

2 Symptoms and Underlying Causes

Clinical signs of fever in cats include lethargy, anorexia, and atypical behavior changes such as hiding or unusual excitement.

Disease processes that cause fever include infection, inflammation, neoplasia, and immune-mediated disease.

Drugs commonly implicated in feline fever include cephalosporins, griseofulvin, methimazole, penicillin, propylthiouracil, sulfonamides, tetracycline, and thiacetarsamide.

Fever of unknown origin (FUO) describes a cat with fever for 1 to 2 weeks with no obvious or detectable cause and no abnormality on routine diagnostic testing; this syndrome is fairly common in cats.

3 Treatment Strategy

Treat the underlying disease: identifying and treating the primary disease is the key to resolving the fever. Fluid support: febrile cats are often anorexic and dehydrated, so fluid therapy is needed. Antibiotic therapy: because bacterial infection is the most common cause of fever, cats with FUO may receive a short course of broad-spectrum antibiotics. Nutritional support: needed when anorexia is prolonged or expected. Antipyretics are used only when temperature exceeds 41 C; common options are aspirin, ketoprofen, and meloxicam.

4 Important Precautions

Antipyretic therapy can interfere with monitoring the course of disease and with assessing treatment response. If temperature stays below 41 C it generally will not damage the brain or organs and is actually beneficial. Nonsteroidal anti-inflammatory drugs are cleared slowly in cats and should be used cautiously to avoid toxicity, especially kidney toxicity.