Feline transfusion medicine. Blood types and their clinical importance.

Anemia is the most common indications for a blood transfusion in cats and fresh whole blood is typically administered. Recent experimental studies and clinical reports have elucidated the importance of feline blood types in transfusion medicine. The AB blood group system, the only recognized feline blood group system, consists of three blood types: type A is most common, type B is frequently found in certain breeds, and type AB occurs rarely. The blood type frequently varies geographically among domestic shorthair cats and between breeds. Because of the presence of naturally occurring alloantibodies, only AB-matched transfusions are effective and safe. Blood typing is now readily available and incompatibilities are easily recognized with blood crossmatching tests. Owing to the general presence of strong anti-A alloantibodies in type B cats, type A blood given to a type B cat results in life-threatening acute hemolytic transfusion reactions. Immediate withdrawal of a transfusion and supportive care may save a patient. Other transfusion reactions, unrelated to AB mismatch, cause only mild and transient signs. Peculiarities of feline blood banking also are reviewed.