In cats, only one major blood type system has been identified. Blood type incompatibilities are known to be responsible for transfusion reactions and neonatal isoerythrolysis in this species. Blood type B cats have naturally occurring antibodies against the type A red cell antigen, hence problems may occur with the first transfusion or pregnancy.
Most cats are blood type A. However, several cat breeds, including the Birman, Devon Rex, and British Shorthairs, have significant numbers of blood type B cats. Thus, breeders must be aware of blood type incompatibility problems. Blood type A cats may carry an allele for blood type B, but the current serological typing methods cannot distinguish these blood type B carriers. This study will look at cats from unrelated populations, remote populations, and different breeds to distinguish which mutations cause the blood types. If successful, the resulting DNA-based assay will be performed earlier, and will detect blood type A cats carrying an allele for blood type B.