Red blood cell antigens are structures located on the red blood cell surface. They are genetically determined and species specific. Blood typing determines the blood type of an animal using antibodies that recognize major antigens on the cell surface. Knowing the blood type of a patient is important, especially during blood transfusion where antigen-antibody reactions may occur due to variation of blood type antigens between the recipient and the donor.

During a blood transfusion, the red blood cell antigens of the recipient may react with plasma antibodies from the donor. The blood transfusion reactions are classified as non-immunological or immunological, and categorized as acute or delayed. An acute reaction occurs in the presence of pre-existing antibodies against erythrocytes, while delayed reactions may occur 4 to 6 days later, after the production of antibodies against red blood cells antigens. Later in life, if a donor is subsequently exposed to the same antigens, an acute hemolytic transfusion reaction may ensue.

Canine Blood Type:

In dogs, the main blood types are parts of a specific system designated by the letters DEA for Dog Erythrocyte Antigen, followed by a number. More than a dozen different canine blood types have been described, and the major blood types are DEA1.1, 1.2, 3, 4, 5, and 7. The more clinically relevant canine blood type is DEA 1.1 since it’s associated with the strongest antigenic response and the more severe blood transfusion reaction. The canine red blood cells are either positive or negative for a specific blood type (e.g.DEA 4+ or DEA 4-). Approximately 45% of dogs are DEA 1.1+.

To prevent and anticipate transfusion reactions due to blood type incompatibilities:

Because there is no known natural anti-DEA 1 antibody in dogs, the first transfusion may not result in an immediate reaction. However, antibodies can develop and result in a delayed transfusion reaction in less than a week following the first mismatched transfusion. If a DEA 1- dog previously exposed to DEA+ blood receives DEA 1+ blood, a severe hemolytic reaction could occur in less than an hour. Blood typing is recommended for blood donors and for dogs in need of a blood transfusion. In dogs, universal donors are DEA 1.1. Ideally, transfused blood should be DEA 1- but a DEA 1+ dog may receive DEA 1+ or DEA 1- blood while DEA 1– dog should never receive DEA1+ blood.

Feline Blood Types:

Blood types in cats include A, B, and AB. Most cats are type A. Few cats are type AB. The frequency of type B cats varies according to the breeds and the geographical location. For example, type B are found in a few breeds (e.g. Persians, Himalayans, Abyssinians, Exotic and British Shorthairs, Cornish and Devon Rex) and in some geographical areas. Australia, France and Turkey have been reported to have the highest incidence of type B cats. There are also breeds in which type B cats have not been reported: Siamese, Burmese, American Shorthairs, Oriental Shorthair, Russian Blue, and Tonkinese.

Usefulness / Utilization:

To prevent and anticipate blood transfusion reactions due to blood type incompatibilities: Unlike dogs, cats have natural antibodies against red blood cell antigens they do not possess. Type B cats have strong anti-A antibodies which are strong hemagglutinins and hemolysins against type A red blood cells. Type A cats have weak anti-B antibodies which are weak hemagglutinins and hemolysins against type B red blood cells. There is no universal donor in cats. All cats must be blood typed and/ or crossmatched before any transfusion. Type A cats should receive blood from type A cats and type B cats should receive blood from type B cats. Type B cats should never receive Type A or Type AB blood since this can lead to severe and even fatal transfusion reaction. Type A cats transfused with type B blood may suffer a mild transfusion reaction, the transfused RBC life span could also be considerably shortened. Type AB cats do not have anti-A and anti-B antibodies. Therefore, Type AB cats may receive either type AB or type A blood. 

Since most cats are Type A, access to blood from a Type A donor should be readily available if blood transfusion is needed. Type B donors may also be required, based on the breed and the geographic location of the recipient.

Mating Risk & Neonatal Isoerythrolysis:

In kittens, neonatal isoerythrolysis happens when antibodies of maternal origin, acquired from the colostrum, react with the erythrocytes antigens. Neonatal isoerythrolysis is reported in type A or AB kittens born from type B queens with strong natural anti-A antibodies. Mating type B queens with type A or AB toms may lead to neonatal isoerythrolysis if type A or AB offsprings are allowed to nurse from their dam. Determining the blood type of the queen and the tom before the mating can minimize the risk of neonatal isoerythrolysis.