Glossary of Terms

Whole blood is composed of red blood cells, white blood cells and plasma.

Red Blood Cells (RBCs) are produced by bone marrow and contain hemoglobin. Each cell receives oxygen as it travels through the lungs. From there, the RBCs carry the oxygen to all cells in every part of the body.

Hemoglobin, a molecule which makes up 95% of a RBC, functions as the oxygen carrier. Fully oxygenated hemoglobin is what gives blood its red colour.

White Blood Cells (WBCs) are a small part of the blood volume (approximately 1%). WBCs are mostly produced by bone marrow and have many different jobs such as destroying bacteria, viruses, fungi and old blood cells.

Platelets are essential in the process of coagulation (clotting) of blood. These tiny cells are activated in bleeding situations, plugging small leaks in blood vessels.

Plasma is the vehicle for carrying all the blood components. Water makes up 95% of plasma. Plasma also contains sugars, fats, various proteins, hormones, vitamins, minerals, and clotting factors. All these components travel in the plasma to nourish and maintain the function of all the cells of the body.

Antibodies are proteins contained in plasma. Their job is to fight off "foreign" substances (antigens); for example, bacteria, parasites, viruses and foreign blood cells.

Canine Blood Types

Different types of proteins (antigens) are carried on the surface of RBCs. Canine blood types are determined by which of those proteins appear in an individual dog. Although a total of eleven different red cell proteins (called Dog Erythrocyte Antigens or DEAs) have been identified, only 6 are practical and useful to test for: The six DEAs are: 1.1, 1.2, 3, 4, 5 and 7.

Depending upon which DEA a dog has, its blood type is either positive (+) for a certain antigen or not.

Examples: 1.1+, 4+ OR 1.1+, 4+, 5+ OR 4+

Only one protein, (DEA 1.1) can be tested "on the spot" by an in-house blood test. This factor is the most significant because a majority of dogs are 1.1+ and blood of this type is the most likely to cause a reaction if given to a dog with an incompatible blood type.

Most dogs are positive for DEA 4. If a dog tests positive for only DEA 4, they are considered a "Universal" donor. These donors can give blood to dogs of any blood type without significant risk. DEA 4 positive (all else negative) dogs make ideal donors in a life-or-death emergency when the blood type of the recipient is not known and there is no time to perform the blood-typing tests.

Dogs do not have natural-occurring antibodies against any of the red cell proteins (DEAs). This means if a dog has never been transfused before, he can be given an incompatible blood type and in most cases will not suffer any immediate or serious effects. After a few days, however, his body will form antibodies to the foreign red cell antigens. The antigens will attack the transfused RBCs, destroying them quickly. If that same dog needed a subsequent transfusion and were given incompatible blood again, a severe, sometimes fatal reaction would occur. If the dog had originally been given his matching blood type the transfused cells would have lasted and been more beneficial in his system. In addition to the routine blood typing test, a procedure called "cross matching" is always performed when the patient is one who has received unmatched blood in the past. Cross matching is routine even in typed animals when time permits.

Dogs that are positive for more than just 1.1 and 4 will only be used as plasma donors because plasma does not contain the RBC cell wall proteins (DEAs). These extra DEAs can cause a transfusion reaction in the recipient.

Feline Blood Types

Cat blood types fall into three separate blood group systems; A. B or AB. Unlike dogs, no single cat blood type is a universal donor. Cats of one blood type have naturally-occuring antibodies to another type; therefore, the blood type of the donor must correspond with that of the recipients.

Type A blood is the most common in cats. Type B cats are uncommon and fewer than 1% of cats are type AB. Blood types can be more common in specific breeds; for example Siamese cats are almost all type A and British Shorthair cats are more likely to have type B blood than the rest of the cat population.

Reasons to Transfuse

Transfusion is necessary when significant blood loss has occurred.

Some scenarios include:

1. Trauma

Hit by a car
Running through a glass door causing extensive cuts and injury
Dog, raccoon, or coyote inflicted wounds

2. Extensive surgery with complications

3. Ingestion of rodenticides
Causes inability of blood to clot

4. A ruptured abdominal or cardiac tumour
Causes blood loss internally

5. Diseases where red blood cells or platelets are destroyed by the body's immune system