Humans, dogs and cats have different blood groups. These are important as the blood groups determine the compatibility of blood.
Felines have three major blood groups: A, B and AB.
Group A is the most common.
Group B is quite common in certain pedigree breeds.
Group AB appears to be rare in all breeds.
Because pedigree cats in different countries are sometimes bred from quite different gene pools, in some cases the frequency of blood group A and group B cats can vary between countries so the likely blood group of any individual cat should never be assumed.
Blood group B cats all have naturally occurring high levels of anti-A antibodies in their blood. This means that if a type B cat were to receive blood from a type A donor, this could cause a severe and even fatal reaction because the immune system would recognise the type A blood as ‘foreign’ and attack it.
Some group A cats also have naturally-occurring anti-B antibodies, meaning that they too may develop severe reactions if given incompatible blood.
Hence, cats should always be blood typed and/or cross-matched if they need to receive blood and when they donate blood to ensure any transfusion is compatible. You may bring your cat to the vet to check their blood type.
Approximate frequency of type B cats in various breeds
Note this is for guidance only and will vary between countries and regions
Breeds with only type A or a low frequency of type B (less than 10%)
Breeds with an intermediate frequency of type B cats (10-25%)
Breeds with a high frequency of type B cats (more than 25%)