MSH: Viral disease of horses caused by the equine infectious anemia virus (EIAV; INFECTIOUS ANEMIA VIRUS, EQUINE). It is characterized by intermittent fever, weakness, and anemia. Chronic infection consists of acute episodes with remissions.,NCI: A horse disease caused by a retrovirus which is transmitted by biting flies. The acute phase symptoms include high fever, anemia, weakness, and swelling of the legs. The subacute phase symptoms include splenomegaly, anemia, and weight loss. The chronic phase symptoms include recurrent fevers and anemia.