A Retrospective Study on Bacteriology, Clinicopathologic and Radiographic Features in 28 Cats Diagnosed with Pyothorax

SIMPLE SUMMARY: The cat is a popular pet in Malaysia. Pyothorax is one of the most common respiratory conditions of cats in Malaysia. The etiological agents, particularly bacteria, of local feline pyothorax cases have never been studied. Therefore, in the present study we aimed to identify the bacteria involved in feline pyothorax cases, detect the antimicrobial susceptibility of the bacteria involved and study the radiographic findings related to these cases. Clinical records of cats diagnosed with pyothorax between 2013 and 2020 were analysed. The cats were presented with respiratory signs. Blood results showed significant inflammatory patterns and radiographs revealed different findings for each cat. The common bacteria and the antimicrobial susceptibility of the bacteria were determined in this study. Reporting the most common bacteria involved will give clinicians useful information that will further help in the selection of appropriate treatment and help clinicians understand the pathogenesis of pyothorax in the Malaysian cat population. ABSTRACT: This retrospective study aimed to determine the etiological, clinicopathological, and radiographic features and outcome of feline pyothorax cases. Medical records from twenty-eight cats with pyothorax aged from 4 months to 10 years (median 10 months) diagnosed between 2013 and 2020 were reviewed. Dyspnoea (75.0%), abnormal lung sounds (75.0%) and open-mouth breathing (64.3%) were the predominant respiratory signs. Leucocytosis (61.5%), particularly monocytosis (68.0%), and hyperglobulinaemia (65.4%) were among the most prominent findings in blood analysis. Bilateral pleural effusion was found in 67.9% of the thoracic radiographs. A total of 47.4% of the cytological samples revealed the presence of bacteria, while all had positive bacterial growth. Pasteurella multocida, E. coli, Streptococcus spp., and Staphylococcus spp. were the predominant aerobic bacteria isolated from pleural effusion samples. A chest tube was placed in 64.3% of the cats and 66.7% of cats with chest tubes survived. In total, 46.4% of cats with pyothorax recovered. Amoxicillin–clavulanate was the antimicrobial of choice against aerobic bacteria found in this study and should be given in combination with antimicrobials that cover anaerobic bacteria. Chest tube placement is crucial for treatment success. Cytological results and bacterial culture may not be consistent; thus, bacterial culture should be performed for every case.