The AB blood group system of cats.

Holmes (1950) and Eyquem, Podliachouk & Milot (1962) classified feline erythrocytes into two types according to their reactions with naturally occurring antibodies in cats' plasmas. Eyquem et al. (1962) designated the two antigens, A and B, and this nomenclature has been retained in the present study. The blood group system, AB, was investigated in more detail, both genetically and serologically. Frequencies of 73.3% A and 26.3% B were found in a survey of 1895 Brisbane cats and in addition, a new phenotype, AB, was discovered with a low incidence of 0.4%. The results of the serological testing and limited family information suggested that the AB phenotype is inherited and not due to blood chimaerism. Preliminary genetic studies indicated that the A gene is dominant to the B in the usual situation and hypotheses to explain the occurrence of the AB phenotype are discussed. The incidence of naturally occurring antibodies was investigated in cats, with 95% of blood type B having anti-A and only 35% of type A having anti-B. No subgroups of the A and B antigens were detected and no blood group substances were found in the salivas of 37 cats. There was no evidence of any serological relationship of the feline A and B antigens with the human ABO antigens.