Blood Types and Donor Cats

Cats have blood types that should often not be mixed

Does blood type really matter other than as a matter of curiosity? Yes! Any time a cat needs a blood transfusion, that cat ideally should receive blood of the same type.

Blood types in cats are labeled as A, B, or AB. Cats with type B blood usually have high levels of natural antibodies to type A blood, which means even one incorrect transfusion may result in a reaction that causes the rapid destruction of red blood cells.

Cats with type A blood have low levels of naturally occurring antibodies to type B, so they usually can accept one transfusion of type B without problems. They may subsequently produce antibodies to Type B blood, however, and a second transfusion may lead to a reaction with destruction of blood cells.

Cats with the rare AB blood type do not usually have antibodies to either type A or B, and can usually receive transfusions from either type A or type B donors with no problem.

Blood type incompatibility can be a problem for kittens who have a different blood type than their queen. Once they start nursing, they can develop fatal destruction of red blood cells (see upcoming article on neonatal isoerythrolysis).

Type A Is Prevalent

The frequency of blood types varies both among cat breeds and geography. Over 90% of all cats are type A, including nearly all domestic shorthair and longhair cats, Siamese, and other Oriental breeds. Siamese, Burmese, Russian Blue, Ocicat, and Oriental Shorthairs are believed to be only type A.

Most other cats are type B, with a lower prevalence of type AB. A survey by researchers at the University of Pennsylvania showed that the breeds with the highest percentage of type B cats were the Devon Rex and British Shorthair. Ragdolls had the highest prevalence of type AB in this survey.

A Winn Feline Foundation report looked at the geographic distribution of blood type of cats in North America: “The frequency of the feline blood groups in non-purebred cats varies both by breed and by location. In North America, the lowest frequency of type B cats is in the Northeast and North Central/Rocky Mountain regions. Higher frequencies of type B cats are found on the West Coast, peaking in the Northwest with 6% type B cats. Frequencies also vary worldwide, with portions of England and Australia having up to 35% type B cats.”

Donor Cats

You may want to consider having your cat “work” as a blood donor to help save the lives of other cats. Some hospitals collect and maintain blood supplies or have in-house donor cats, while others have blood donors on call to come in and donate when needed. Most donor cats are used no more than four times a year, so there’s often need for another.

Ideal donor cats weigh around 10 lbs. provided that their body condition is healthy. Donor cats should be young adults, generally 1 to 8 years old. Ideally, they should be friendly cats with a low stress level. They should be healthy, vaccinated, and not on any medications other than flea, tick, and/or heartworm preventives.

Donor cats should be indoor-only cats and should only live with other indoor-only cats to avoid exposure to many pathogens. They should have been tested for and be negative for feline leukemia and feline immunodeficiency virus as well as mycoplasma.

At the time of a donation, blood tests will be done to evaluate your cat’s kidneys and liver, and blood counts will be done to make sure she is healthy. Cats are often sedated or anesthetized to donate blood to minimize stress, and about 40 to 50 ml of blood is withdrawn. The donor cat is then given intravenous fluids to help restore her fluid balance and monitored carefully during recovery.

Some hospitals offer special perks for donor cats, like free screening bloodwork and possibly free vaccines or preventive medications. And, of course, these cats and their owners get tremendous gratitude from the owners of the cats whose lives they helped save.

Want to Know Your Cat’s Blood Type?

You can get your cat blood typed, and many clinics will do this to have donor cats of known blood type available. The Cornell Animal Health Diagnostic Laboratory can do blood typing using a blood sample collected by your veterinarian. You can read more at If you’d like to do blood typing via a genetic test, ask your veterinarian about the Veterinary Genetics Laboratory, University of California, Davis. Go to