Is animal blood the same as human blood?

Animal blood and human blood share some similarities, such as the presence of red blood cells, white blood cells, and platelets, but they differ in composition and function. The types of hemoglobin, blood cell types, and immune responses vary between species. For example, while humans have type A, B, AB, and O blood groups, animals have different blood group systems altogether. Therefore, while there are fundamental similarities, the differences are significant enough that animal blood cannot be directly substituted for human blood.