Aortocavitary fistula secondary to vegetative endocarditis in a rabbit

A 4-year-old intact male mini lop rabbit (Oryctolagus cuniculus) was presented with a 2-week history of severe progressive lethargy. A right parasternal continuous heart murmur and an irregular rhythm were detected on physical examination. Echocardiography identified vegetative aortic and tricuspid valve (TV) endocarditis. There was an aortocavitary fistula between the right sinus of Valsalva into the right ventricle, creating a left-to-right intracardiac shunt. Based on the echocardiographic findings, it was suspected that the infection originated in the aortic valve, eroded through the periannular tissue, and secondarily infected the TV. Pleural and peritoneal effusion secondary to right-sided congestive heart failure was also found during the echocardiogram. Atrial fibrillation, conducted with a left bundle branch block morphology, was identified using electrocardiography. Necropsy findings directly correlated with the echocardiographic diagnosis; marked periodontal disease was also identified. Aerobic culture of the aortic and tricuspid vegetations resulted in significant growth of Haemophilus parainfluenzae. Haemophilus spp. belong to a group of similar gram-negative coccobacillus bacteria (HACEK group), which can act as an uncommon cause of endocarditis in humans. HACEK endocarditis is most commonly associated with oral infection and/or dental procedures in people. This is the first case report of a rabbit with periannular complications of infective endocarditis. It remains unknown whether dental disease resulted in endocarditis in this patient.