Blood Groups in cats
Genetics of blood groups in cats
The importance of the discovery of blood groups in cats is particularly evident in two areas. The first is blood transfusion and the second is blood group intolerance in newborn kittens. When type A blood is transferred to a type B recipient, a severe immune reaction of the body occurs. And in the case of an immune reaction in newborn kittens, this is a big problem for the breeder, as hemolytic disease will occur in such affected kittens. The fetal red blood cells pass through the placenta into the mother's bloodstream and induce the production of anti-Rh antibody, which can pass through the placenta into the fetus and react with the Rh antigen. Similarly, the maternal blood meets the blood of the feline embryo and the antibodies contained in the colostrum (first milk) meet the organism of the feline newborn.
Thanks to new knowledge, it may be possible to prevent such parental contact in the future.
This disease mainly affects newborns with blood type A, who are born from the mating of a cat of blood type B with a cat of blood type A. Especially in cat breeds where the presence of blood type B is greater than 10 %, this phenomenon is not negligible.
Affected feline neonates are born healthy and receive their first food from their mother
( colostrum) maternal antigens that cause the destruction of their red blood cells. All the cases reported so far have affected newborns with blood group A - because, as already mentioned, cats with blood group B have very strong antibodies against blood group A. Theoretically, it is possible for kittens to have blood group B - a cross between an A cat and a B cat - but the group A antibodies are not very effective against blood group B.
Within a few hours or days, the disease manifests itself with completely non-specific symptoms: disappearance of the sucking reflex, apathy or restlessness, brownish urine colour, anaemia and eventually death. At the end of the first week of the disease, the tip of the tail may die. Interestingly, in a litter at risk, not all kittens with blood group A may become ill. The causes of this phenomenon cannot yet be satisfactorily explained, but may be related to the biochemical nature of the production of red pigment and subsequently red blood cells or antigens.
If we have not yet determined the blood groups of the parental pair and we suspect the possibility of haemolytic disease in the kittens, it is appropriate to remove the kittens from the mother after birth and attach them to a surrogate mother or feed them artificially. Usually 24 hours to three days is sufficient. Only the colostrum is dangerous. If we suspect that the red blood cells are breaking down, we can use a simple test : we gently massage the kittens' tummies with moistened cotton wool to encourage the excretion of urine. In healthy kittens it should be colourless. In kittens affected by haemolytic reaction, it will be brownish due to dead red blood cells.
The tail tip may also be dead - the tail tip is the terminal site of blood circulation and if its cells are not sufficiently oxygenated, they die.
Blood groups in cats were discovered as early as 1953 by Holmes, but the importance of this discovery was not appreciated at the time. It was not until later scientific work by Auer and Bell in 1981 that feline blood groups A , B and the rarer group AB were defined.
The feline blood group system differs from the human blood group system in that blood group 0, which is relatively common in humans, has not yet been found in cats. However, in our feline friends, as in humans, the blood groups are genetically determined and the difference is caused by specific antigens on the surface of the red blood cells with which any antibodies contained in the individual's blood plasma are able to react. The blood group A allele is dominant over the b allele, meaning that blood group B is determined only by the homozygous bb genotype, whereas blood group A can also be determined by the heterozygous Ab configuration. This means that kittens born from mating blood group B parents can also only carry blood group B. On the other hand, from mating of blood group A parents we can also obtain individuals with homozygous configuration bb or heterozygous individuals with a predisposition for blood group B (genotype Ab ).
Not much has been published in the literature about blood group AB, which is relatively rare in the cat population. Scientists believe that in the case of this blood group there is codominance of both alleles (both acting simultaneously without one being superior to the other) or that this fact is determined by another, as yet unknown allele. The problem of determining blood groups has been addressed by leading authorities in this field. We can name MVDr. Urs Giger from the Veterinary School in Philadelphia, Pennsylvania or Dr. Judith Leidinger from the In Vitro Laboratory in Vienna. However, the final result of the research on blood group AB in cats is not yet known.
As already mentioned, the determination of the AB blood group has only been elucidated at a hypothetical level. It is known that kittens with blood group AB do not necessarily occur in matings of parents with blood group A and b.
Blood group AB is found in those breeds where blood group B is also present. It is recessive with respect to blood group A and dominant over blood group B, which means that this blood group can be carried by both AB AB homozygotes and AB b heterozygotes /we present the AB symbol as a working symbol for a hypothetical gene determining blood group AB/. In biochemical research it has been shown that blood group AB reacts less strongly to anti-A serum than blood group A and reacts about as strongly to anti-B serum as blood group B. This means that kittens born with blood group AB from blood group B mothers are at high risk of neonatal red blood cell breakdown, as maternal iso and allo antibodies recognize blood group AB surface antigens and destroy the newborn's red blood cells.
According to the results of studies by American scientists, the breeds most affected by this disease are :
1 - 5% type B : Maine Coon, Manx, Norwegian Forest
10-20% type B : Abyssinian, Scottish Crested, Persian, Japanese Bobtail, Birman, Somali cat
25 - 50 % Type B : British Shorthair, Devon Rex, Cornish Rex
Unfortunately, studies on the frequency of blood type AB are not yet available.
The German IG Ragdoll breeders had 151 Ragdolls blood tested and obtained the following results :
16.5% blood group B
19.2% of blood group AB