Sterile pyogranulomatous pericarditis in a dog

A 4‐year‐old, neutered, female crossbreed dog was presented with a chronic history of weakness and hyperthermia. Echocardiography showed mild pericardial effusion. Fluid analysis revealed a marked non‐septic neutrophilic‐macrophagic exudate. Pericardial fluid and blood culture were negative. Leishmania spp., Ehrlichia spp., Bartonella spp., Babesia spp., Mycoplasma spp. and Hepatozoon spp. reverse transcription polymerase chain reaction tests were also negative. Initially, a good response to pericardiocentesis, empirical antibiotic therapy and prednisone was observed. However, pericardial effusion recurred and a subtotal pericardiectomy was performed. Histopathology of the pericardial tissue showed a severe pyogranulomatous inflammatory process. Periodic acid–Schiff and Ziehl–Neelsen stains, pericardial tissue culture and fluorescence in situ hybridisation were negative. Clinical signs recurred, and prednisone was prescribed again. Twenty‐two months after prednisone withdrawal, the dog remains asymptomatic. This is the second report of idiopathic sterile pyogranulomatous pericarditis in a dog, and the first report using fluorescence in situ hybridisation to evaluate the presence of bacterial pericarditis.