Studies on some blood parameters of crossbred calves with experimental Theileria annulata infections

Subcutaneous inoculation of 1 ml of ground Theileria annulata tick tissue s tabilate (0.75 tick equivalent) into crossbred calves (n = 6, average age 5 3 days) resulted in the development of acute theileriosis. The percentage p arasitaemia was 71.7%+/-3.3% on day 20 after inoculation. Macroschizonts we re observed in lymphocytes and monocytes. Phagocytosed schizonts were obser ved in neutrophils, along with cytoplasmic vacuolation in monocytes and neu trophils. There was progressive decrease (p <0.05) in the haemoglobin and p acked cell volume, along with a marked reticulocytosis. Serum analysis reve aled a decrease (p <0.05) in the concentrations of calcium, cholesterol and triglycerides, while there was an increase (p <0.05) in the concentrations of blood urea nitrogen as compared to day 0 values. The total serum protei ns, albumin and serum immunoglobulin concentrations and the albumin-to-immu noglobulin ratio showed marked decreases (p <0.05). Coagulopathies included thrombocytopenia and an increased prothrombin time, along with a non-signi ficant increase in the bleeding time and activated partial thromboplastin t ime during the terminal stages of the disease. There was an increase in the osmotic fragility of erythrocytes during the disease. Morphological altera tions in the erythrocytes were observed with the developing parasitaemia.