Fever of unknown origin in dogs: 50 cases

Although in veterinary medicine the term "Fever of unknown origin" (FUO) is still liberally used for any febrile patient where no diagnosis has been set after routine diagnostics, the term "true FUO" should be assigned to those cases in which no aetiology is found after extensive diagnostics. The aim of this study was to investigate the occurrence of FUO in dogs, to research the structure of the FUO population, as well as to explore clinical signs and their duration, and the prior treatment and incidence of different diagnoses and their outcomes. Also, this study was conducted in order to explore the amount of diagnostic procedures (with their effectiveness) required to reach a final diagnosis with the intention of helping design and prioritize diagnostics of FUO in dogs in Croatia. Final diagnosis was reached in 94% (47/50) of dogs with a total of 626 diagnostic procedures used. Immune-mediated diseases occurred most frequently (56%), followed by infectious diseases (24%), ncoplastic diseases (10%) and congenital diseases (4%), with only 6% of "true FUO". Body temperature ranged between 39.6 degrees C and 42.0 degrees C. The most common symptoms were nonspecific (anorexia and lethargy in 88%, pain in 78%, and gait disorders in 60%). The most frequent test performed was hematology while hemoculture was performed the least. Cytology and/or pathohistology were the most effective tests in achieving the final diagnosis (76.32%). The duration of clinical signs before the diagnosis/proper treatment was 4-1825 days. The outcome was favorable in 62%, unfavorable in 32% and unknown in 6%.