Because problems can occur when 2 carriers of type B are bred together or if a type A female gives birth to type B kittens, we blood type test our Sires and Queens. Why is blood typing important to Sphynx breeders? Read below:
Blood Group Incompatibility in Cats
Blood group incompatibility (BGI) can present a problem to breeders. One of the causes of Fading Kitten Syndrome is "neonatal isoerythrolysis". This means the kittens have a different blood type from their mother and the antibodies in her milk attack those kittens' red blood cells. The symptoms are jaundice, brown urine and rapid deterioration and death. In less severe cases, the affected kitten's tail-tip drops off. The diagnosis is confirmed by blood-typing the mother and affected kittens.
In controlled breeding programs, BGI can be prevented by blood-typing the parents before mating them. Kittens receive one blood-type gene from each parent.
The common blood types are A and B. Cats with blood type A have naturally occurring anti-B antibodies at a low titer and cats with blood type B have naturally occurring anti-A antibodies at a high titer. Blood-type A genes are a dominant to blood-type B genes and the trait is autosomal (non-sex-linked).
A third rare type "AB" is also known. Cats with the rare "AB" type do not have anti-A or anti-B antibodies and are thus universal recipients for blood transfusion. It should be noted that the nomenclature of cat blood groups is confusing; the "AB" type is not the result of presence of the A and B blood groups. There is no null phenotype.
BLOOD TYPES AND CARRIERS
A cat may be blood-type A but still carry the recessive gene for blood-type B. If two carriers of blood-type B are bred together, there is a probability of some kittens being blood type B.
* A cat homozygous (pure-breeding) for type A has 2 matching "A" genes; Aa
* A cat heterozygous for type A (carrier of type b) has one dominant "A" gene and one recessive "b" gene; Ab
* A cat homozygous (pure-breeding) for type B has 2 matching "b" genes; B (bb).
* A cat with type A phenotype may have the genotype AA (homozygous i.e. non-carrier) or the genotype Ab (heterozygous i.e. carrier).
* A cat with type B phenotype can only be genotype bb (homozygous).
The inheritance and full implications of the rare AB blood type is not yet understood. Note that "Ab" means a blood-type A cat carrying the recessive "b" gene and is different from a blood-type "AB" cat. Blood type B is shown by upper case "B". The recessive gene for that blood type is shown by lower case "b".
HOW BLOOD GROUPS ARE INHERITED
This table explains the different genotypes Ab and bb.
*Red cells are genotypes to be cautious of.
| PARENTS: | Type AA Mother |
Type Ab Mother |
Type B (bb) Mother |
Type AB Mother (rare) |
| Type AA Father |
AA | AA or Ab | Ab | Unknown |
| Type Ab Father |
Aa or Ab | AA, Ab or B (bb) |
Ab or B (bb) | Unknown |
| Type B (bb) Father |
Ab | Ab or B (bb) | B (bb) | Unknown |
If a male is type Ab, then half of the kittens produced with a type B female will show signs of BGI. If he isn't a carrier, then none of the kittens will be at risk, but they will all be known carriers of type B. However, and it is a big however, due to the random way genes are passed on, it may take several matings to completely rule him out as a carrier.
When 2 Ab cat are mated together, on average one quarter of all kittens will be type B. Because type Ab queens have less anti-B antibodies than type AA queens, some of those kittens might survive. However, the queen will build up antibodies as a result of having type B kittens, and if she has type B kittens in the future, they are more likely to develop full-scale neonatal isoerythrolysis and die. The only way to tell whether a queen is AA or Ab is to test mate her to a type B male.
The blood type is an additional consideration when outcrossing cats to broaden or reinvigorate a gene pool. Will the outcross cat introduce type B into a breed that previously had no incidence of type B? A highly desirable outcross cat may introduce the required traits, but may also introduce an unwanted blood type.
BLOOD-TYPING KITTENS
Kittens can be blood-typed at birth using a drop of blood from the umbilicus. If the kitten is the same blood type as the mother, it is safe for it to suckle from her. If the blood types differ, it is advisable that the kitten does not suckle from her for its first 16 hours of life as that is when its gut is permeable enough to allow antibodies from her colostrum to get into the bloodstream. Since maternal antibodies are important during the kitten's early life, hyperimmunoglobulin sera is available for kittens that are hand-reared due to Blood Group Incompatibility. After 16 hours it is considered safe to allow it to suckle from their mother.
Portions of this article is used by permission from Sarah Hartwell of MessyBeast.Com.
Test Blood Type of breeding pair via