Frequently asked questions for the QuickVet®/ RapidVet® Feline Blood Typing™ test
What is the AB system?
Cat blood groups are classified using the A, B, AB blood type system. This blood typing system defines three blood types based on the presence of specific inherited antigens at the surface of the red blood cells. 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. A third rare type AB is also known. Cats with the rare AB type do not have anti-A or anti-B antibodies. There are however no null phenotype and as a consequence, there is no universal donor.
The A and B blood groups are genetically determined. Blood type A is the most common among cats, but the frequency varies significantly by breed and geographic location. Breeds that do not have the B type are Siamese, Burmese, American Shorthair, Oriental Shorthair and Tonkinese.
Breeds with high incidence of the B blood type are Abyssinian, Japanese Bobtail, Birman, Persian, Scottish Fold, British Shorthair, Cornish Rex, Exotic Shorthair, Somali, Sphynx, Turkish Van, Turkish Angora and Devon Rex.
The inheritance of the rare AB group is not well understood and the incidence of the AB type is reported to be less than 1 %. Breeds that have the very rare type AB blood include Birman, British Shorthair, Scottish Fold, Somali, and Sphynx. Somalis are more likely than average to have the rare type AB blood.
When is a blood transfusion needed?
A blood transfusion provides an immediate supply of red blood cells, which are essential for carrying oxygen around the body. A blood transfusion can therefore be life-saving in severe anemia. However blood contains many other elements which may also be useful. When blood is transfused the three major elements that can be provided are:
Red blood cells (erythrocytes): these are the cells that carry oxygen around the body and are given to treat anemia. A simple blood measurement called the packed cell volume (PCV) can be used to estimate the number of red blood cells. In a normal cat, the PCV is usually between 25% and 45%. Although each individual situation varies, a blood transfusion will normally be required if the PCV falls below 10-15%
Plasma: this is the fluid component of blood (within which the red cells are suspended). It contains many proteins with essential functions. Albumin - this is the major protein in blood, and importantly helps to hold fluid (water) within the circulation. Other chemicals and hormones may be transported around the body being bound to albumin. Clotting factors - these are critically important proteins in the blood that cause blood to clot when a blood vessel is damaged. Inflammatory mediators - a variety of proteins are produced during inflammation to help fight infections and regulate the inflammation
Platelets: these are very small cells in the blood that work alongside clotting factors to allow blood to clot and prevent prolonged bleeding after injury
Why is it important to type cats before transfusion?
Blood Transfusion Risks
Cats that are transfused, even once, with an incompatible blood type, are at risk for a transfusion reaction. Cats with type B blood exhibit an immediate and catastrophic systemic anaphylactic reaction and a Hemolytic Transfusion Reaction (HTR) when transfused with type A blood, because of their natural high-tittered anti-A antibody. As an outcome death of the patient is extremely likely.
Cats with type A blood exhibit a natural low-tittered anti-B antibody response when transfused with type B blood. In this case, the reaction is mild but the transfused cells will have a shortened life span. The recipient will develop moderate titers of anti-B antibody that will result in a serious reaction if a subsequent incompatible transfusion is administered
Serious problems can result from accidental or mismatched mating. A mating of a type B queen with a type A tom will result in their type A kittens being at risk for neonatal isoerythrolysis (NI), commonly known as “fading kitten syndrome”. The maternal naturally occurring highly tittered anti-A antibody occurs in the colostrum where from it can be absorbed by the newborn kittens. The absorbed antibody attacks the kitten’s type A erythrocytes.
Although the kittens can seem normal at birth, they develop signs after nursing, fade and die within the first days of life. Determining the blood type of the queen and the tom prior to mating, coupled with appropriate genetic counseling, can minimize the risk of NI. Furthermore, immediate blood type determination of the newborn kittens will alert the client to remove the kittens and to begin surrogate nursing where necessary.
Does the method of blood sample collection matter?
Proper technique for blood collection is essential for accurate results. Blood should be drawn as a-traumatically as possible in a syringe or EDTA tube. Samples with visible clotting, hemolysis or debris should be discarded and a fresh sample obtained. The sample should be tested within 12 hours.
When would clinics use the Feline Blood Typing™ test?
The practice of veterinary transfusion medicine has undergone tremendous growth in recent years, and as a result the understanding of the importance of identifying blood types has increased.
Clinics should therefore use the test for:
- Determination of blood type before a transfusion.
- As part of the pre-operation test panel to ensure that relevant information is on file if an emergency requiring a transfusion arises.
- Determination of blood type as part of routine testing so that the information is on file.
- Prior to breeding decisions.
What animals can be tested with the The QuickVet®/RapidVet® Feline Blood Typing™ Test?
The QuickVet®/RapidVet® Feline Blood Typing™ test only works with feline, as the blood type is specific to each specie.