Feline blood groups: the risk of type B in transfusion
5-year-old British Shorthair with severe anaemia (haematocrit 10%) due to haemorrhage. It has never been transfused. The only donor available at the clinic is type A.
Which statement about the transfusion is correct?
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A. The recipient must be typed before the first transfusion, because a type B cat can have a fatal haemolytic reaction to type A blood
Correct. Type B cats have strong naturally occurring anti-A alloantibodies, and a small volume of type A blood is enough to cause a severe reaction. Type B is more common in breeds such as the British Shorthair, Devon Rex and Cornish Rex.
B. As it has never been transfused, there is no risk of reaction and typing is unnecessary
This reasoning applies (with caveats) to dogs, which lack clinically relevant natural alloantibodies. In cats, antibodies exist without previous exposure.
C. A type B cat can receive type A blood if premedicated with antihistamines and corticosteroids
Premedication does not prevent alloantibody-mediated haemolysis. A type B cat must only receive type B blood.
D. Type AB cats are universal donors
There is no universal donor in cats. AB red cells carry both A and B antigens and would react with the antibodies of type A or B recipients.
lightbulb Key takeaway
Always type both feline donor and recipient and, where possible, crossmatch even before the first transfusion (other antigens, such as Mik). The same mechanism causes neonatal isoerythrolysis: type A kittens nursing colostrum from a type B queen.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.