Thrombocytopenic Purpura in a Suckling Calf

Abstract

A calf of two weeks old showed purple spots and hemorrhages in several parts of the skin. At necropsy, petechiae and ecchymosis were observed in the skin, subcutaneous tissue and serosal surface of visceral organs. Hematologically, no thrombocytes could be detected in blood smears and clot retraction did not occur. Light microscopy revealed multiple hemorrhages in the subcutis, submucosa and serosa of the intestinal tract, and in the other internal organs. In the bone marrow, megakaryocytes appeared normal but slightly increased in number, whereas thrombocytes were decreased. The number of thrombocytes markedly decreased, when blood samples from normal calves were mixed with blood plasma of the diseased calf or when the rabbits were injected intravenously with the serum from the diseased calf. In the former case, aggregates of thrombocytes were frequently seen. It suggested the presence of a platelet agglutinating factor in the patient plasma. Based on the data collected, the present case was diagnosed as thrombocytopenic purpura.