Signs and diagnosis of tularemia infection in cats from 2000 to 2021

Abstract

Objectives The objectives of this study were to describe the clinical features of cats diagnosed with tularemia, and to compare the clinical features of cats with and without tularemia and identify characteristics increasing the likelihood of a tularemia diagnosis. Methods Diagnostic laboratory data and medical records were retrospectively reviewed of cats tested for tularemia between 2000 and 2021. Clinical features including signalment, presenting complaint(s), physical examination findings and clinicopathologic data were described for cats with tularemia diagnosed by culture and/or PCR. Clinical features were also compared between PCR+ vs PCR− cats and logistic regression was used to identify features that predicted PCR+ status. Results A total of 18 cats were diagnosed with tularemia. The affected cats had a mean age of 5.8 ± 4.9 years, with a slight male predominance. Most were domestic shorthair cats and had outdoor access. Common presenting complaints included lethargy and anorexia, while physical examination findings frequently revealed fever, peripheral lymphadenomegaly and oral ulcers. Laboratory findings varied, with notable abnormalities including neutrophilic inflammation observed on cytology and widespread acute systemic pathologic changes in necropsy results. Leukopenia and neutropenia were more common in PCR+ vs PCR− cats, and these factors were 7.4 times (confidence interval [CI] 1.2–62.3) and 10.0 times (CI 1.4–83.2) more likely to occur in PCR+ vs PCR− cats, respectively. There were no significant differences between the groups in other parameters including anemia, thrombocytopenia, band neutrophilia and hyperbilirubinemia. Conclusions and relevance This study provides a more comprehensive description of tularemia in cats than has been available to date. In particular, leukopenia and neutropenia are significantly associated with tularemia-positive cats. These clinical features should be considered and raise suspicion for tularemia in cats. These findings may be valuable for the timely diagnosis, treatment and prevention of tularemia outbreaks in cats and humans.