Cat Blood Types: What Owners Should Know
Blood group typing in cats is an important but often overlooked aspect of feline medicine. Just as humans have blood types like A, B, O, and AB, cats have their own blood group system. Understanding cat blood types is essential for safe blood transfusions, breeding decisions, and managing neonatal isoerythrolysis (NI), a potentially fatal condition in kittens.
The Feline AB Blood Group System
Cats primarily have three blood types within the AB system: Type A, Type B, and Type AB. The vast majority of domestic cats worldwide are Type A, making it the most common blood type. Type B is less common but found more frequently in certain pedigree breeds such as the British Shorthair, Persian, and Sphynx.
Type AB: Very rare, occurring in less than 1% of cats. These cats are universal recipients in blood transfusions but universal donors only for other AB cats.
The Importance of Blood Typing Before Transfusions
Cats have naturally occurring antibodies against the blood type they don’t have. A Type B cat receiving Type A blood will experience a severe and potentially fatal transfusion reaction, even from the very first transfusion. This is why blood typing before any transfusion is non-negotiable in modern veterinary practice. Similarly, Type A cats receiving Type B blood may experience a milder reaction but one that still affects the success of the transfusion.
Neonatal Isoerythrolysis (NI)
NI is a condition that occurs when a Type B queen mates with a Type A tom, producing Type A kittens. The queen’s colostrum (first milk) contains high levels of anti-A antibodies. When Type A kittens nurse, they absorb these antibodies, which attack their red blood cells, leading to haemolytic anaemia, jaundice, and potentially death within the first few days of life.
To prevent NI, breeders of breeds with higher Type B prevalence should blood type both parents before mating. If a mismatch is found, Type A kittens should be temporarily separated from the queen for the first 24 to 48 hours, receiving alternative colostrum from a Type A queen, before being returned to their mother once they can no longer absorb antibodies from the gut.
Blood Types in Pedigree Breeds
Some breeds have a higher prevalence of Type B blood, making this knowledge particularly relevant for breeders and owners of these cats. Breeds known to have higher rates of Type B include British Shorthair, Devon Rex, Cornish Rex, Ragdoll, Abyssinian, Somali, Norwegian Forest Cat, Scottish Fold, and Sphynx. Regular blood typing of breeding cats in these breeds is strongly advised.
Practical Steps for Cat Owners and Breeders
If you own a pedigree cat from a breed with higher Type B prevalence, consider having your cat blood typed, especially if you plan to breed. Ensure your vet is aware of your cat’s blood type, especially before any elective surgery or procedure that might necessitate a transfusion. If you are a breeder, make blood typing a routine part of your pre-breeding health assessment. This small step can prevent the heartbreak of losing kittens to NI and improves safety in emergencies where your cat may need a blood transfusion.
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