UF Veterinarians: Blood Type Mismatch In Breeding Is Leading Cause Of 'Fading Kitten Syndrome'

April 29, 1999

GAINESVILLE—When an entire litter from Joni Easterling’s prized Persian cat died last July, the Orange Park cat breeder was understandably upset.

Little did she know her cat’s blood type could have been behind the loss.

“We did not know she was a type B kitty,” said Easterling, who has been breeding Persians for nine years and who inadvertently bred Linsee of Carnavale to a male cat with type A blood. “That was her fourth litter, and the other litters had done well. It was just very strange.”

Easterling later brought 13 of her cats to the University of Florida College of Veterinary. Of those 13, only Linsee was identified as having type B blood; the others had type A.

“I now have only type A kittens in my breeding program, and as far as my future plans, I don’t intend to bring anything into my cattery unless it has been blood typed,” she said.

Many cat breeders and veterinary practitioners aren’t aware that cats have different blood types — and that incompatible blood types in breeding is a leading cause of the condition known as fading kitten syndrome in purebred cats during the first week of life, said Cynda Crawford, a postdoctoral associate at UF’s College of Veterinary Medicine.

“The kittens typically appear healthy and vigorous at birth, but some kittens suddenly die after nursing while others fade’ and die three to seven days later,” Crawford said.

Cats are known to have three blood types — A, B, and AB. In the United States, nearly 95 percent of all domestic mixed-breed cats are type A. All Siamese, Burmese, Tonkinese, American Shorthair and Oriental Shorthair cats tested so far have type A blood.

However, type B blood is found in 10 to 50 percent of many purebreds, including Devon Rex, Persian, Sphynx, Abyssinian, Cornish Rex, Exotic Shorthair, Birman and Somali. There are a handful of purebred cats for which blood type B frequency has not been determined.

“Similar to humans, cats have naturally occurring antibodies to blood types other than their own,” Crawford said. “Incompatibility between type A and type B cats can cause potentially fatal reactions under two circumstances: transfusion of type B cats with type A blood, and breeding of type A males to type B females to produce type A kittens.”

In breeding, type A is dominant over type B. That means the offspring of a type B female bred to a type A male will carry type A blood.

“When the type A kittens nurse the type B mother, they ingest a substance from the mother’s milk that contains antibodies against their blood type,” Crawford said. “These anti-A antibodies are absorbed into the kittens’ blood during the first day of life, and rapidly begin to destroy the kittens’ red blood cells.”

A quick and easy blood test manufactured by DMS Laboratories was donated to the UF veterinary college for use at a cat owners’ symposium earlier this year.

“All you need are two drops of blood, which then are mixed with antibodies that are fixed onto the surface of the testing card,” Crawford said. “This is a very fast, simple way to determine a cat’s blood type and can be performed by a veterinarian in his or her clinic.”

Cat breeders might want to consider keeping only type A cats in their catteries, Crawford said.

“It behooves breeders to consider not breeding a type B female, because they’re going to have to find a type B male to breed with her all the time,” she said. “The more often you breed a type B mother, the more you’re increasing the pool of type B cats and hence the risk of future disease.”

Veterinarians need to be aware that if they have clients who are losing kittens, it is possible that the mother cats are type B and they should investigate further, Crawford added.

“The general practitioners also need to be aware that their anemic feline patient who needs a transfusion may actually need blood from a type B cat,” Crawford said. “It’s important to know beforehand what type blood the cat has and to have access to a donor cat with the same type of blood.”