The determination of blood groups is important when performing blood transfusions and even in pregnant females, since the viability of the little ones will depend on it. Although there are only three blood groups in cats: A, AB and B, if a correct transfusion with compatible groups is not carried out, the consequences will be fatal. On the other hand, if the parents of the future kittens are, for example, an A or AB cat with a B cat, a disease that causes hemolysis in the kittens could be generated: neonatal isoerythrolysis, which usually causes the death of the little ones in their first days of life.
How many blood groups are there in cats?
In small felines we can find three blood groups according to the antigens they present on the red blood cell membrane:A, B and AB.
Cat breeds of group A
Group A is one of the three the most frequent in the world, being European and American shorthair cats the ones that mostly present it, as:
- European cat.
- American shorthair.
- Maine coon.
- Manx.
- Norwegian Forest.
On the other hand, Siamese, Oriental and Tonkinese cats are always group A.
Breeds of cats from group B
The breeds of cats in which group B most predominates are:
- British.
- Devon rex.
- Cornish rex.
- Ragdoll.
- Exotic.
Cat Breeds Group AB
The AB group is very rare to find, being seen in cats:
- Angora.
- Turkish Van.
The blood group that a cat has depends on its parents, since they are inherited. Each cat has one allele from the father and one from the mother, this combination determining its blood group. Allele A is dominant over B and it is even considered that with AB, while the latter is dominant over B, that for a cat to be type B it must have both B alleles. So:
- A cat A would present the following combinations: A/A, A/B, A/AB.
- A cat B is always B/B because he is never dominant.
- An AB cat will be AB/AB or AB/B.
How to know the blood group of a cat?
Today we can find several tests for the determination of the specific antigens of the red blood cell membrane, which is where locate the blood group of a cat. blood in EDTA is used and placed on cards designed to reveal the cat's blood group depending on whether or not the blood is agglutinated.
In cases where the veterinary clinic does not have these cards, they can take blood sample from the cat and send it to the laboratory for indicate which group you are from.
Is it important to test cats for compatibility?
It is necessary, because cats have natural antibodies against the membrane antigens of red blood cells of other blood groups.
All group B cats have strong antibodies to group A, which means that if they come into contact with the blood of a cat B with one from a cat A, it will cause enormous damage and even death in the cat of group A. Those of group A present antibodies against group B but weaker, and those of group AB do not present antibodies neither against group A nor against to B. This is important when doing transfusions, due to the serious problems they can cause.
Blood transfusions in cats
In some cases of anemia, cats require a blood transfusion. Felines with chronic anemia have lower hematocrits (volume of red blood cells in total blood) than those with acute anemia or sudden blood loss, becoming hypovolemic (decreased blood volume). The normal hematocrit of a cat is around l 30-50 %, so that cats with chronic anemia and a hematocrit of 10-15% or those with acute anemia with a hematocrit between 20 and 25% should be transfused. Together with the hematocrit, the clinical signs should be observed, which, if the cat presents, indicate that it needs a transfusion. These signs indicate cellular hypoxia (low oxygen in cells) and are:
- Tachypnea.
- Tachycardia.
- Weakness.
- Stupor.
- Increased capillary refill time.
- Serum lactate increased.
In addition to determining the blood group of the recipient for compatibility with the donor, the donor cat must have been checked for any of the following pathogens or infectious diseases:
- Feline leukemia.
- Feline immunodeficiency.
- Mycoplasma haemofelis.
- Candidatus Mycoplasma haemominutum.
- Candidatus Mycoplasma turicensis.
- Bartonella hensalae.
- Erhlichia sp.
- Filaria sp.
- Toxoplasma gondii.
Blood transfusion from cat A to cat B
A blood transfusion from a cat A to a group B cat is devastating, because cats B, as we have mentioned, have very strong antibodies against group A antigens, which leading to group A transmitted red blood cells being rapidly destroyed (hemolysis), causing an immediate, aggressive, immune-mediated transfusion reaction that ends with the death of the transfused cat
Blood transfusion from cat B to cat A
If the transfusion is performed in reverse, that is, from a group B cat to a type A cat, the transfusion reaction is mildand it is not effective due to the reduced survival of transfused red blood cells. Also, a second such transfusion would cause a much more severe reaction.
Blood transfusion from cat A or B to cat AB
If type A or B blood is transfused into an AB cat nothing should happen, since it does not have antibodies against group A or B.
Feline Neonatal Isoerythrolysis
Isoerythrolysis or hemolysis of the newborn is called the incompatibility of the blood group at birth that occurs in some cats. The antibodies that we have been discussing also pass into the colostrum and breast milk and, in this way, reach the offspring, potentially causing problems as we have seen in transfusions.
The big problem of isoerythrolysis occurs when a cat B has been mated with a cat A or AB and therefore her kittens they are mostly A or AB, so when they suckle from the mother during the first days of their life they can absorb numerous anti-group A antibodies from the mother and trigger a immune-mediated reactionto their own group A antigens on red blood cells, causing them to break (hemolysis), known as neonatal isoerythrolysis. With other combinations, isoerythrolysis and death of the kitten do not occur, but a relatively large transfusion reaction occurs that destroys red blood cells.
Isoerythrolysis does not manifest itself until the kitten ingests those antibodies from the mother, so at birth they are about he althy and normal cats. Once they have taken the colostrum, the problem begins to appear.
Feline neonatal isoerythrolysis symptoms
In most cases, these kittens will weaken as the hours or days go by, stopping suckling, becoming very weak, pale from anemia. If they survive, those mucous membranes and even skin will turn icteric (yellow) and even their urine will turn red from the breakdown products of red blood cells (hemoglobin).
In some cases, the disease causes sudden death without any previous symptoms that show that the cat is unwell and something is wrong its interior. In other cases, the symptoms are milder and appear with the dark tip of the tail due to necrosis or cell death in the area during the first week of life.
The differences in severity of the clinical signs depend on the variation of the anti-A antibodies that the mother has transmitted from the colostrum, the quantity of the same that the offspring have taken and their capacity to absorb the themselves in the organism of the small feline.
Feline neonatal isoerythrolysis treatment
Once the problem has manifested, it cannot be treated, but if the caregiver realizes it during the first hours of life of the kittens and remove them from the mother and feed them milk formulated for kittens, it will prevent them from absorbing more antibodies that aggravate the problem.
Prevention of neonatal isoerythrolysis
Before treating, which is practically impossible, what should be done in the face of this problem is its prevention. To perform it, you need to know the blood group of cats. However, since this is often not possible due to unwanted pregnancies, the best way to prevent it is neutering or spaying cats
If the kitten is already pregnant and we are in doubt, we should prevent the kittens from drinking their colostrum during their first day of life, removing them from the mother, which is when they can absorb disease antibodies and those that cause damage to their red blood cells if they are group A or AB. Although before doing this, it is ideal to determine which kittens are group A or AB with blood group identification cards from a drop of blood or from the umbilical cord of each kitten and remove only those from those groups, not those from B that would not have any hemolysis problem. After this time, they can be reunited with the mother since they no longer have the capacity to absorb maternal antibodies.
