Avian hematology involves blood sampling from veins in the comb, wing, tibia, or jugular vein. Anticoagulants like EDTA or heparin are used. Avian blood contains nucleated red blood cells, white blood cells, and thrombocytes suspended in plasma. Hemoglobin in birds has two types, A and D, and shows high oxygen cooperativity. Coagulation tests like prothrombin time monitor the blood clotting pathway.