Experimental babesiosis in coyotes and coydogs.

One splenectomized and 6 intact coyotes (Canis latrans), and 2 coydogs were experimentally inoculated with a recent isolate of Babesia gibsoni. The disease was mild in intact animals, was fatal in the splenectomized coyote, and was characterized by a regenerative hemolytic anemia with the PCV decreasing to 16% in intact animals and to 6% in the splenectomized coyote. Peak parasitemia ranged from 3% to 21% of erythrocytes infected and was inversely correlated to PCV. Serum lactate dehydrogenase, bilirubin, and globulin concentrations were increased in all infected animals. Three weeks after inoculation, specific antibody titers increased to 1:65,536 and remained elevated in the chronically infected animals. The splenectomized coyote had progressive weakness until death, 24 days after inoculation. Intact animals had splenomegaly and anorexia at the height of infection. The splenectomized coyote had generalized edema, omental petechiae, renal and hepatic degeneration, membrano-proliferative glomerulonephritis and congestion, extramedullary hematopoiesis, lymphoid hyperplasia, and severe hemosiderosis in an accessory spleen. The only consistent change in the intact animals was splenomegaly.