Clinical changes in experimental sheep infection by Trypanosoma evansi (TeApMantecal01 and R38), Trypanosoma equiperdum (TeAp-N/D1), and Trypanosoma vivax (Tucacas) isolates. Sheep were inoculated intravenously via jugular vein with 1 x 106 parasites obtained from infected rats. The course of the infection was monitored for 65 days without treatment for T. evansi and T. equiperdum infections. The T. vivax inoculated sheep were treated (Trypamidium ®) at 36 days postinfection to prevent animal death and safeguard its health. The clinical parameters monitored interdaily were as follows: (a) rectal temperature was determined using a column thermometer and expressed in °C. (b) Changes in hematocrit values: PCV was estimated using microhematocrit tubes every 2 days and expressed as the average percent. (c) Red cell count was determined by direct counting from blood using a Neubauer chamber and expressed in cell/ml of blood. (d) Haemoglobin concentration was determined by cyanmethemoglobin method and expressed in g/dl.