Cats have three blood types: A, B and AB. Type A covers more than 90% of domestic cats in most countries, type B reaches 25 to 50% inside a few breeds, and AB stays under 1% almost everywhere. The numbers matter on exactly two days of a cat's life: the day it needs a transfusion, and the day it is born to a queen with the wrong type.
There is no universal donor cat. Cats carry antibodies against the blood type they lack before they have ever been transfused, so a first mismatched transfusion can already cause a reaction within minutes.
How the three types are distributed
Regional surveys differ, and a clinic that types 100 cats will not match the textbook exactly. The broad pattern holds: domestic shorthairs are overwhelmingly type A, above 90% in the US, the UK and most of Europe. Type B climbs sharply in a handful of pedigree breeds, where 25 to 50% of individuals can be B depending on country and bloodline. Type AB stays below 1% in every population tested.
Two practical consequences follow. A breeder cannot predict a kitten's type from coat color or pedigree lines, only from a test. And a practice that keeps only type A donors can help an A cat but cannot safely transfuse a B cat, which is why larger hospitals keep 1 to 2 B donors on call.
Breed patterns worth knowing
Breed is a hint, never a substitute for a test. The table summarizes the ranges most often reported; treat every cell as approximate and confirm with a 5-minute typing card.
| Breed group | Type A share, approximate | Type B share, approximate |
|---|---|---|
| Domestic shorthair and longhair | above 95% | under 5% |
| Siamese, Oriental, Burmese | above 99% | under 1% |
| British Shorthair | 75 to 90% | 10 to 25%, higher in the UK |
| Devon Rex | 55 to 75% | 25 to 45% |
| Cornish Rex | 60 to 80% | 20 to 40% |
| Persian and Exotic Shorthair | 85 to 95% | 5 to 15% |
| Abyssinian, Bengal, Maine Coon | above 95% | under 5% |
Why the second transfusion is the dangerous one
Type B cats carry strong naturally occurring anti-A antibodies; type A cats carry weaker anti-B. A B cat given A blood can react within 5 to 15 minutes: restlessness, salivation, vomiting, a weak rapid pulse, then red-brown urine as hemoglobin passes into the kidneys, and collapse. An A cat given B blood often reacts slowly, with transfused cells surviving only days, so the episode looks like a transfusion that simply failed to raise the packed cell volume.
The first transfusion is not automatically safe. Cats are one of the species where a first exposure can already trigger a reaction, and the risk climbs on the second because antibodies have been boosted. That is why the plan is never just to give some blood: it is type, then crossmatch, then transfuse.
The newborn window: 24 to 48 hours
Neonatal isoerythrolysis happens when a type B queen mates with a type A tom and the kittens inherit A. The first 24 to 48 hours of colostrum pump anti-A antibodies into the kitten's gut, and from there into the blood. Kittens look normal at birth and fade at 1 to 3 days: dark urine, yellow gums, weakness, refusal to nurse, and sometimes blackened tail tips where small vessels have been damaged.
Prevention costs one test. Type the queen before breeding. If she is B, either use a B tom or withhold colostrum for 24 to 48 hours, hand-feed a commercial kitten milk replacer every 2 to 3 hours, and return the litter to the mother once the gut stops absorbing whole antibodies at roughly 16 to 24 hours.
Typing, crossmatching and dose
Typing takes about 5 minutes with an in-clinic card or cartridge. A crossmatch adds 20 to 45 minutes and has two halves: major, donor cells against recipient serum, and minor, donor serum against recipient cells. Both run before a first transfusion, and again before a second one given 3 or more days after the first.
A typical dose is 10 to 15 mL per kg of body weight, delivered over 2 to 4 hours. The first 15 minutes go slowly, near 0.5 mL per kg, with temperature, pulse, breathing rate and gum color checked every 5 to 10 minutes. Blood is warmed toward 37 C and never above 40 C.
Red cells have a short shelf life in practice
A cat's own red cells circulate for roughly 70 to 80 days, against 110 to 120 in a dog. A unit drawn from a 4 to 5 kg donor is only 40 to 50 mL, and most practices use it within 3 days of collection; stored units are usually discarded after 3 to 4 weeks. That is fine, because the goal is rarely a cure. A transfusion buys 7 to 14 days of stability while iron, bone marrow or the underlying cause is worked up.
In a sensitized cat the transfused cells can vanish within 3 days. That is why packed cell volume is rechecked at 24 hours and again at 72 hours, alongside bilirubin and total protein: a PCV that rises and then falls back tells you the blood was destroyed, not that the cat recovered.
Which cats should be typed, and when
- Every breeding queen and tom, once, at 6 months or older, with the certificate kept in the file.
- Any cat facing surgery where blood loss is plausible, so a donor can be arranged in advance.
- Donor cats, retested every 12 months, with FeLV and FIV status checked at the same visit.
- Cats with immune-mediated anemia, before steroids start, because a transfusion may follow within days.
- Multi-cat homes that include a B cat, so every owner knows which cat cannot receive which blood.
Signs that need a vet today
Pale gums, a resting heart rate above 200 beats per minute in an adult or 220 in a kitten, weakness, or refusal to eat for 24 hours after a transfusion. Jaundice in the gums, ear pinnae or whites of the eyes is a same-day problem. If you are unsure whether the gums are pale, press them for 2 seconds and count how long the color takes to return; beyond 2 seconds is a reason to call. Our guide to anemia signs in cats walks through the at-home checks, and blood pressure measurement explains why anemic cats need that reading too.
Steps to take this week
1) Ask your vet to write your cat's blood type into its record even if no transfusion is planned; the test costs less than a bag of food. 2) If you breed, type every adult once and store the result with the vaccination card. 3) Learn the 2-second gum check and repeat it monthly. 4) If a transfusion is proposed, ask for the type and the crossmatch result in writing. 5) For a cat over 10, pair the typing with baseline bloodwork and use the cat age chart to judge how much reserve the cat actually has.
Frequently asked
Can my cat receive blood from a dog?
No. Cat and dog red cells are incompatible, and feline plasma contains antibodies that would destroy canine cells almost immediately. Cats need a feline donor, ideally matched for A, B or AB, and a crossmatch is run before the transfusion rather than after.
Is a first transfusion always safe if the cat has never been transfused?
Not in cats. Unlike dogs, cats have naturally occurring antibodies against the type they lack, so an unmatched first transfusion can cause a reaction within 5 to 15 minutes. Typing plus a major and minor crossmatch before every unit is the standard safeguard.
How do I know if my kitten has neonatal isoerythrolysis?
Watch the first 3 days. Affected kittens are normal at birth, then turn weak, pass dark red-brown urine, develop yellow gums and refuse to nurse. Call the vet immediately; survival depends on stopping colostrum and supporting the kitten with fluids and warmth.