**7.1 Blood transfusion**

Leptospirosis is a zoonosis with worldwide distribution. It is more prevalent in the developing countries. Hemorrhagic manifestations constitute the common clinical feature in leptospirosis [70]. In cattle, acute hemolytic syndrome of leptospirosis has been reported characterized by fever, icterus, anemia, and hemoglobinuria [71]. Without effective treatment, hemolytic syndrome in cattle may result in death. A high mortality rate of severe disease was determined to be associated with certain serotypes of *Leptospira* [72]. The disease, for instance, causes a decrease in erythrocyte and platelet counts, leading to anemia and hemorrhagic diathesis, respectively.

Elevated bilirubin levels result from hemolysis and hepatorenal failure, indicating the characteristic nature of clinical signs [73]. Blood transfusion was reported to be quite effective in cases of life-threatening anemia in cattle. Previous reports suggest that timely transfusion of whole fresh blood be administrated to overcome severe hemolytic leptospirosis. Indeed, transfusion providing the vital components such as erythrocytes, platelets, and plasma contributes to repair the present collapses, that is, anemia, hemorrhagic diathesis, septicemia, and hepatorenal failure, in affected cattle [71]. A PCV value of 15% or less developing acutely may require transfusion, while chronic anemia can be tolerated in cattle without any transfusion [74].
