Fatal acute clinical babesiosis in an adult gelding pony living in an endemic area

Abstract

Equine piroplasmosis is a haemoprotozoal disease caused by Theileria equi and Babesia caballi. Clinical presentations vary in severity according to infectious load, host immunity and endemicity. In endemic regions, equine piroplasmosis is rarely acute or peracute in presentation. Here we report a case of a 10-year-old pony gelding presented for fever and acute inspiratory dyspnoea. Clinical signs of hypovolemic shock were observed. Blood smear examination revealed a mild anaemia and thrombocytopenia with the presence of intraerythrocytic inclusions resembling Babesia caballi merozoites. Acute lung injury, ischaemic myocarditis, acute renal failure, pancreatitis and myopathy were detected. We made a presumptive diagnosis of acute babesiosis, with secondary systemic inflammatory reaction and multiple organ dysfunction syndromes. Supportive therapy was initiated, but imidocarb was not administered due to potentially fatal adverse reactions in a horse in shock. Anaemia worsened, with the development of acute pulmonary oedema, respiratory distress and disseminated intravascular coagulation. The gelding was euthanised and post-mortem examination confirmed the formation of microthrombi within small vessels, leading to venous stasis and vasculitis.