Breed distribution does not vary as much by location because of the international exchange of breeding cats. Over 10% of the domestic shorthair cats in Australia, Italy, France and India are type-B. There is, however, geographic variation in the prevalence of type-B domestic shorthaired cats. The distribution of feline blood types varies by geographic region and breed (Table 1).8-9 Type-A is the most common type among most cats. This test is easier to interpret than the card method, although it requires a specially designed centrifuge that may be cost-prohibitive in some settings.7 An evaluation of various blood typing methods for the cat concluded that the gel column test is reliable when compared to the gold standard Penn tube assay.6 If the card-typing system is used, type-AB and type-B results should be confirmed by a referral laboratory as some cross-reactions have been known to occur.6 A recently introduced option for patient-side blood typing is the gel column agglutination test (DiaMed-Vet® feline typing gel, DiaMed, Switzerland). In addition, genetic testing is now available to identify blood types A and B using buccal swabs, although it cannot distinguish between A and AB blood groups.5 Patient-side testing may be performed with a card typing system (RapidVet®-H, DMS Laboratories, Flemington, NJ). Diagnostic laboratories use various serological methods based on agglutination reactions. Various methods are now available to determine blood type, both in a referral laboratory setting and patient-side. A third type, AB, occurs rarely and expresses both the A and B antigens.4 However, the heritability of type-AB is not well understood. The A-allele is dominant over the b-allele so that cats with genotypes A/A and A/b will be type-A, while only the homozygous b/b will have the type-B phenotype. Another potentially important group called MiK has recently been identified.3 The blood groups are genetically determined species-specific red blood cell surface antigens. There are three well-known, clinically important blood groups in cats: A, B, and AB.1-2 Despite the nomenclature, the antigens in the feline AB blood group are not serologically related to the human ABO blood group antigens.

Blood type rarest to most common