Infective endocarditis (IE) is caused by invasion of the valvular endothelium by microbes, resulting in proliferative or erosive lesions and consequently valvular insufficiency. The mitral and aortic valves are almost exclusively infected in small animals. Vegetative lesions may result in embolism or metastatic infection involving multiple body organs, producing a large variety clinical signs. Endocarditis has a low incidence (0.04–0.13% of all dogs referred to one veterinary teaching hospital). The incidence in cats is considerably lower. Aetiology; Pathophysiology; Clinical signs; Diagnostic approach; Treatment; Monitoring and management; and Prognosis are all considered.