What Causes a Fever in Cats?

1 Causes of Fever

Signs include lethargy, poor appetite, and odd behavior like hiding or agitation, plus symptoms of the underlying disease. Processes behind fever: infection, inflammation, tumor, and immune-mediated disease. Drugs that can induce it include cephalosporins, griseofulvin, methimazole, penicillin, propylthiouracil, sulfonamides, tetracyclines, and thiacetarsamide — tetracycline most often.

2 Specific Diseases

The top cause of unexplained fever is a systemic viral infection such as FIP or leukemia; check the fundus, since these often cause retinitis. FeLV brings recurrent or chronic infection, abortion, anemia, vomiting, diarrhea, breathing trouble, and weight loss; confirm with a FeLV test, bone marrow, or biopsy.

FIP shows heavy abdominal and chest effusion, non-regenerative anemia, high globulins, possible vague neuro signs, and mild liver or kidney failure. Toxoplasmosis brings breathing trouble, jaundice, swollen abdominal lymph nodes, neuro signs, iritis, retinitis, abortion, and low white cells and red cells.

Polyarthritis shows progressive lameness with swollen, painful carpus and hock joints and erosions.

3 Treatment

Treat the underlying disease — that’s the crux. Feverish cats often won’t eat and dehydrate, so give fluid support.

Antibiotics: since bacteria are the most common cause, a short course of broad-spectrum antibiotics is reasonable for unexplained fever. For prolonged or expected anorexia, add nutritional support.

Antipyretics only above 41°C: aspirin (10 mg/kg every 48 h PO), ketoprofen (1 mg/kg daily for 5 days), or meloxicam (0.2 mg/kg daily, then 0.1 mg/kg for 4 days).