The CBC blood test for dogs, also called a complete blood count, checks the number and types of blood cells present in the dog. This test is important when diagnosing illnesses.
Red Blood Cells
A function of the CBC test is to evaluate the red blood cells. When the red blood cell count is abnormal, it is indicative of certain problems. In a CBC blood test, the method in which the red blood cell count is determined is called a hematocrit, or packed cell volume. If the hematocrit is low, that means there aren’t enough red blood cells in the body and the dog is anemic. If the count is high, there are too many red blood cells. This is usually the case in dogs who are dehydrated, in shock, have diseases of lungs or who are in higher altitudes.
White Blood Cells
The CBC blood test also monitors the amount of white blood cells
present. White blood cells, also called leukocytes, help to defend the
body against bacteria, viruses and fungi. If a dog has an elevated
white blood cell count, it could mean that there is an infection in the
body or it is stressed by metabolic toxins. There are five different
types of leukocytes—neutrophils, eosinophils, basophils, lymphocytes
and monocytes— and each helps the body in its own way. If the values of
one type of leukocyte are elevated, it can help the doctor determine
what kind of problem is going on in the dog.
Neutrophils help to
defend the body against bacterial infections. The cells will actually
engulf bacteria and other materials to keep them from causing problems.
An elevated neutrophil count is usually indicative of a bacterial
infection or some extreme form of stress.
Elevated eosinophils
are seen when an animal is suffering from a parasitic infection or
allergies. Like neutrophils, eosinophils also have the ability to
engulf foreign materials in the body.
Basophils are a type of
white blood cell whose function is unknown. Basophils are created in
the bone marrow and are not present in many CBC blood tests.
Lymphocytes
are typically abundant in the blood and are divided into two major
types—B cells and T cells. B cells help to fight off invading organisms
by producing antibodies. T cells help other cells destroy viruses and
other foreign matter that enters the body. An increased lymphocyte
count is usually present when an animal has a prolonged illness, such
as a bacterial or viral infection that has occurred for a long period
of time, or if the dog has certain auto-immune diseases, such as
leukemia.
Monocytes are used to defend the body against
infectious organisms by engulfing the invaders. They also help to cure
inflamed and irritated tissue by secreting protein molecules.
Platelets
Platelets are another component that is checked in the CBC blood test. Platelets assist in clot formation. If this count is low, it could mean that a large amount have been used when trying to heal a cut that is within the body, or that the number is actually low and the dog is in danger of bleeding to death.