Interesting feline cases
Cats with fevers (103° F-106° F) are a common occurrence in everyday practice. Most cases respond to antibiotic therapy or are self-limiting (abscesses, viral infections, post-surgical fevers). However, the most frustrating case is one in which a routine course of antibiotics does not improve the clinical condition of the cat, routine diagnostics do not identify the cause and the fever is ongoing. This is the fever of unknown origin (FUO) case that requires a methodical approach to discover the exact cause of the fever so that proper therapy can be instituted. Your approach may vary based on the clinical presentation of each cat, as well as the patient's geographic location/travel history. You must also consider the cost/benefit of the diagnostic testing as well as the invasiveness of the tests performed. Tests may need to be repeated as the case progresses.
-CBC, Biochemistry profile, Urinalysis, FeLV/FIV test
-Thoracic and abdominal radiographs
Cause of the fever is still not defined, so the hunt continues....
-PCR tests also available for some organisms (Mycoplasma)
-Ultrasound (Abdominal, Echocardiography, areas of swelling)
-CT/MRI – may reduce the need for exploratory surgery
Follow any leads noted on history, physical examination or localizing signs.
While performing the hunt, don't forget to treat the patient.
The fever should break within 3 days if the drug therapy is going to work for that case...
Examples of Diseases that Cause Fever in Cats:
Infectious diseases (localized or systemic)
Inflammatory diseases: pansteatitis, nodular panniculitis, granulomatosis, pancreatitis
Immune-medicated diseases: Immune-mediated polyarthropathy, Pemphigus foliaceus
Neoplastic conditions: Lymphoma, Leukemia, hepatic tumors, gastric tumors, lung tumors, necrotic masses
Miscellaneous conditions: Drug (tetracycline, penicillins, levamisole) or toxin reactions, hyperthyroidism
Points to consider:
Case studies will be utilized in this presentation.
Dunn JK, Gorman NT: Fever of unknown origin in dogs and cats. J Small Anim Pract 28:167-181, 1987.
Feldman BF: Fever of undetermined origin. Compend Contin Educ Pract Vet 2(12)970-77, 1980.
Johannes CM, Cohn LA: A clinical approach to patients with fever of unknown origin. Vet Med 95:633-642, 2000.
Lappin MR: Feline Fevers of Unknown Origin I, II, III. Western Veterinary Conference 2002.
Lappin MR: Fever of Unknown Origin I and II. Western Veterinary Conference 2003.
Lappin MR: Infectious causes of fever in cats. J Vet Int Med 16:366, 2002.
Lunn KF: Fever of unknown origin: a systematic approach to diagnosis. Compend Contin Educ Pract Vet 23(11):976-992, 2001.
McReynolds C, Macy D: Feline infectious peritonitis. Part I, Etiology and diagnosis. Compend Contin Educ Pract Vet 19(9):1007-1016, 1997.
Stubbs CJ, Holland CJ, Reif JS, et al. Feline ehrlichiosis; literature review and serologic survey. Comp Contin Educ Pract Vet 22:307-317, 2000.