Valvular endocarditis associated with Helcococcus ovis infection in a bovine.

A 12-month-old Angus bull calf with a history of fever and lethargy of several weeks' duration was necropsied. Macroscopic findings included general dehydration, congestion, and edema within the craniodorsal lobes of the lung, multifocal ecchymotic hemorrhages on the dorsal epaxial and gluteal muscles, bloody ingesta within the gastrointestinal tract, and a 4- x 4- x 5-cm irregular plaque located on the right atrioventricular heart valve. Microscopically, there were focally extensive pulmonary alveolar infiltrates of histiocytes and neutrophils, large numbers of necrotic hypereosinophilic hepatocytes located within the centrilobular and midzonal regions of the liver, and, within the plaque from the right atrioventricular valve, a large mass formed by abundant laminated fibrin that contained numerous small multifocal aggregates of gram-positive cocci. This report describes the first apparent isolation of Helcococcus ovis from cattle.