Cerebral thromboembolism secondary to infective endocarditis in a pet rabbit

Central vestibular disease is one of the most common problems in pet rabbits. Encephalitozoon cuniculi infection appears to be the most frequent etiology, but other causes have been described. It is known that infective endocarditis can cause thromboembolic disease affecting multiple organ systems in dogs. Secondary embolism from bacterial endocarditis commonly occurs, mainly in the spleen and kidneys; but cerebral thromboembolism disease secondary to infective endocarditis has rarely been reported in dogs. In this case, an 8-year-old, neutered male rabbit (Oryctolagus cuniculus) presented with mild hyperthermia, left head tilt and rolling. Radiographic examination, complete blood count, serum biochemistry and abdominal ultrasound were unremarkable. Magnetic resonance imaging did not show any abnormalities in the central nervous system. An Encephalitozoon cuniculi serology was performed with elevated IgM and IgG titers (1:320; 1:1280 respectively), the patient was hospitalized and treated for encephalitozoonis but the rabbit died 8 days after presentation and the body was submitted for necropsy. Histopathological examination revealed multifocal necrotizing and suppurative myocarditis, with multiple emboli in kidneys, lungs and central nervous system. Polymerase chain reaction, immunohistochemistry, and Ziehl-Neelsen staining of samples from the central nervous system and kidneys yielded negative results for Encephalitozoon cuniculi. Due to the positive predictive value of 92% of indirect fluorescent antibody technique Encephalitozoon cuniculi serology, in this case a false positive was suspected. Based on the results, final diagnosis of cerebral thromboembolism secondary to infective endocarditis was emitted. This is the first report of this process naturally occurring in rabbits, and it should be included in the differential diagnosis of central vestibular syndrome in this species.