ABSTRACT
Vector-borne hemoparasites are commonly found in avian species. Plasmodium spp., the causative agent of avian malaria, are intraerythrocytic parasites that can cause signs ranging from subclinical infection to severe acute disease. In raptor species, most hemoparasites are associated with subclinical infection and are generally not treated when seen on blood evaluation. This case series reviews five cases of hemoparasite infection in snowy owls ( Bubo scandiacus). These animals were infected with a variety of hemoparasites, including Plasmodium, Haemoproteus, and Leukocytozoon spp. Death of one of these birds due to hemoparasite burden led to a change in the monitoring for and treatment of subclinical hemoparasitic infections in this species. Three subsequently infected snowy owls have been treated with primaquine and chloroquine. The birds that were treated survived infection, and parasite burdens in peripheral blood diminished. Postulated reasons for increased morbidity and mortality associated with hemoparasitic infections in captive snowy owls, as opposed to other raptor species, include stress, concurrent disease, novel pathogen exposure, and elevated environmental temperatures.