HEMATOPATHOLOGICAL CHANGES IN DEAD AND MORIBUND CHICKS INDUCED BY CHICKEN ANEMIA AGENT

Abstract

Fifty day-old chicks were inoculated with the Gifu-1 strain of chicken anemia agent [presumed to be a virus]. They began to show anemia and a drop in body weight 10 days postinoculation. Thirty-five died over a period of 12-23 days, mostly between 14-18 days postinoculation. Hematocrit value and red and white blood cell counts were markedly reduced in moribund birds. Peripheral blood polychromatic erythrocytes and granulocytes decreased, accompanied by a fall in hematocrit value and increased with recovery from anemia. Macroscopically, dead and moribund birds revealed yellow bone marrow, marked atrophy of the thymus and bursa of Fabricius and discoloration and swelling of the liver, spleen and kidneys. In some cases, there were partially well-defined necrotic foci in the liver, round hearts, fresh hemorrhages in the proventricular mucosa, erosion on the gizzard mucosa and s.c. edema. Microscopically, marked hypoplasia or aplasia of hematopoietic cells in the bone marrow and severe depletion of lymphocytes in lymphoid organs (thymus, bursa of Fabricius, spleen and cecal tonsils) were commonly seen in affected birds. The anemia induced by chicken anemia agent might be closely related to bone marrow function.