With the introduction of DNA testing in 2006 we are now able to find the group A/b carriers. These cats do not pose a problem  due to neonatal isoerythrolysis when mated. However mating two A/b carriers can produce B kittens in the litter. If breeding with A/b cats it is advisable to DNA test any kittens that are to be used for future  breeding so you know exactly what blood types they are.

There is no problem mating:

 A males with A Females  or A females with B Males

B Males with B Females

A/b Carrier with A or A/b carrier of either sex


A type Males mated to B type Females are the matings where kittens must not be allowed to suckle for the first 16 hrs. They cannot cope with the antibodies in the colostrum for that amount of time. Allowing them to suckle causes the neonatal isoerythrolysis

 A/b Carriers mated to B type females may cause the same problem with half the kittens on average, so it is advisable to treat the kittens the same way as those above.


Link to the DNA Test site http://www.vgl.ucdavis.edu/services/cat/