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Why you should know your cat's blood type

By Catblood.sg · 14 October 2026

Why your cat's blood type matters

Most cat owners know their cat's vaccination history and FIV/FeLV status, but very few know their blood type. It matters most on the worst day: when your cat suddenly needs a transfusion.

Cats have three main blood types in what vets call the AB system: A, B and AB. They are not interchangeable. Giving a cat the wrong type of blood can cause a severe reaction, and in the worst case it can be fatal, even if it's the cat's first transfusion (Laboklin; dvm360).

Knowing your cat's type ahead of time helps in three ways:

  • In an emergency, your vet already knows what kind of donor to look for.

  • If you want to help, you'll know whether your cat could donate to another cat who needs blood.

How rare is each blood type?

Type A is by far the most common. Type B is uncommon, and type AB is rare. How common each type is depends a lot on where a cat lives and what breed it is (UC Davis VGL).

We couldn't find any published study of blood types in Singapore's cats. The closest data comes from studies elsewhere in Asia:

Where

Cats tested

Type A

Type B

Type AB

Source

Bangkok, Thailand (2022–2024 samples)

114 (76 domestic shorthair, 38 pedigree)

93.86%

3.51%

1.75%

Thai Journal of Veterinary Medicine, 2025

Bangkok, Thailand

320 (229 domestic shorthair, 91 pedigree)

97.5%

2.5%

0%

Sangkaew, Chulalongkorn University, 2019

Beijing, China (non-pedigree)

262

88%

11%

0.4%

Zheng et al., 2011, as cited in Gavazza et al., Animals, 2021

For comparison, the Merck Veterinary Manual says about 99% of cats in the US are type A (Merck Veterinary Manual). Among domestic shorthairs in Australia, Italy, France and India, more than 10% are type B (dvm360).

Breed makes a big difference. In the 2019 Bangkok study, every domestic shorthair tested was type A, but 17.1% of Persians and 4.0% of Scottish Folds were type B (Sangkaew, 2019). A study of more than 11,000 cats, mostly from the US and Europe, found type B in 40.4% of American Curls, 33% of Cornish Rex, 30.3% of Devon Rex, 20.3% of British Shorthairs and 20% of Havana Browns (PLOS Genetics, 2021). Type B is rare in Siamese, Burmese and Russian Blue cats (UC Davis VGL).

What blood type means for a transfusion

Cats carry antibodies against the blood type they don't have, from birth and without ever having had a transfusion. That's why a mismatch can be dangerous the very first time.

  • Type B cats have high levels of anti-A antibodies. EveryCat Health Foundation notes these antibodies are very strong in type B cats older than three months (Laboklin; EveryCat Health Foundation).

  • Type A cats have low levels of anti-B antibodies (Laboklin).

  • Type AB cats have neither anti-A nor anti-B antibodies (Laboklin).

Here is what happens with each kind of transfusion, according to a veterinary conference paper by feline specialist Dr Susan Little (dvm360):

Recipient cat

Receives

What happens

Any type

Its own type

Donated red blood cells have a half-life of 29–39 days.

Type B

Type A blood

Severe and possibly fatal. As little as 1 mL can cause breathing problems, breathing that stops, vomiting, diarrhoea, crying out and an irregular heartbeat. The donated cells last only hours.

Type A

Type B blood

A milder reaction within minutes: listlessness and a fast heart and breathing rate. The donated cells have a half-life of only about two days, so the transfusion helps for much less time.

Type AB

Type AB, or type A if AB isn't available

Type B blood is avoided, because its strong anti-A antibodies can destroy the recipient's own red blood cells.

This is why a type B cat like Meshy can only receive type B blood, and why type B donors are so hard to find in an emergency.

Blood typing isn't the only safety check. Cats have other blood groups beyond A, B and AB, including one called Mik, so vets may also run a crossmatch test before a transfusion to check that donor and recipient are compatible (dvm360).

Why most cats are type A

Type B and type AB are rare because they are recessive. A cat has to inherit the right gene variant from both parents to have either type, while a single copy of the type A version is enough to make a cat type A.

It comes down to one gene. A cat's blood type is set by a gene called CMAH. It makes an enzyme that changes a sugar molecule on the surface of red blood cells: NeuAc (the type B marker) becomes NeuGc (the type A marker). Type B cats lack a working version of this enzyme, so their red blood cells keep the type B marker (OMIA; PLOS Genetics, 2021).

The A version wins. Every cat inherits one copy of the gene from each parent. The order of dominance is A, then AB, then B (UC Davis VGL):

/

Blood type

Gene copies the cat carries

Type A

A + A, A + AB, or A + B

Type AB

AB + AB, or AB + B

Type B

B + B only

So a type B cat needs a B copy from both parents. A type A cat can carry a B copy without anyone knowing, and pass it on to its kittens (UC Davis VGL; Laboklin).

The B and AB versions are also uncommon to begin with. In the study of 11,036 cats, the main type B variant made up 12.6% of gene copies, and the AB variant only 1.5%. Most of those cats were pedigree cats from the US and Europe (PLOS Genetics, 2021). A variant that is uncommon, and that only shows up when a cat inherits two copies, produces few type B or AB cats.

Why type B is more common in some breeds and regions than others isn't well understood. A 2021 review of 28 studies points to gaps in the research on feline blood groups, and Southeast Asia is barely covered (Gavazza et al., Animals, 2021).

What this means for you

Most cats are type A, so any single cat is unlikely to be type B or AB. But when a type B or AB cat needs blood, the right donor is hard to find, and every hour spent searching matters.

Here's how you can help:

  1. Ask your vet about blood typing at your cat's next check-up, and keep the result with their health records.

  2. Register your cat's interest at catblood.sg, even if you don't know their blood type yet. We'll follow up to see whether your cat could be a suitable donor.

  3. Share this post with other cat owners.

If your cat needs blood right now, contact your vet straight away.

This post is for general information and isn't veterinary advice. Speak to your vet about your own cat.

[Register your cat's interest →]

Sources

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