Pyrexia in cats: Retrospective analysis of signalment, clinical investigations, diagnosis and influence of prior treatment in 106 referred cases.

Spencer, Sarah E; Knowles, Toby; Ramsey, Ian K; Tasker, Séverine

OBJECTIVES The main aim of the study was to describe the features and diagnoses of a population of cats referred with pyrexia. Other aims were to report and evaluate the utility of clinical investigations performed, and describe any effect of treatment before referral on temperature at presentation and ability to make a diagnosis. METHODS Clinical records of cats with pyrexia (⩾39.2°C) documented at least twice were retrospectively reviewed. Cases were assigned to disease categories (infectious, inflammatory, immune-mediated, neoplastic, miscellaneous and no diagnosis [pyrexia of unknown origin, PUO]) based on diagnosis. The overall value of clinical investigations was assessed by classifying them as 'enabling', 'assisting' or 'no assistance' in achieving each diagnosis. The effect of treatment before referral was assessed for any association with temperature at presentation and ability to make a diagnosis (PUO vs other disease categories). RESULTS One hundred and six cases were identified. The most common cause of pyrexia was feline infectious peritonitis (22 cats, 20.8%) and the largest disease category was infectious (41/106, 38.7%). Inflammatory conditions were found in 19 (17.9%) cats, neoplasia in 13 (12.3%), miscellaneous causes in 11 (10.4%) and immune-mediated disease in six (5.7%). No diagnosis was reached in 16 (15.0%) cats, often despite extensive diagnostic investigations. Cytology and histopathology most often 'enabled' or 'assisted' in obtaining a diagnosis. Most cats (91, 85.8%) received treatment before referral, with antimicrobial treatment given to 87 (82.1%). Prior treatment before referral was not associated with temperature at presentation nor with success in establishing a diagnosis. CONCLUSIONS AND RELEVANCE This is the first study investigating causes of pyrexia in cats. Infectious diseases were most common and immune-mediated diseases were comparatively rare.