Updates on practical ABC blood compatibility testing in cats.

In feline practice, blood groups were considered unimportant until the 1980s. Since then much has been learned. The most important blood group system in cats is the AB (renamed here as ABC) blood group system consisting of blood types A, B and AB (better referred to as C). Type B cats have strong anti-A alloantibodies potentially leading to incompatibility reactions during A-B mismatched transfusions or neonatal isoerythrolysis (NI) in type A and C (AB) kittens born to type B queens. Acute hemolytic transfusion reactions as well as NI have been clinically well documented in cats. Immunological and genetic tests have been established and blood typing and crossmatching test kits have become commercially available. This review updates the current knowledge of these blood types, their genetics, associated incompatibility reactions, and different diagnostic tools for avoiding such reactions in clinical practice.