Complete Blood Count (CBC)
Description: Blood is collected from
an animal and placed into a tube which contains material that stops clots from
forming. The blood cells themselves are then analyzed according to their shape,
size, color, and relative numbers present in the bloodstream (hence the term
Diagnostic Value: Certain diseases can be detected and even initially
diagnosed with a simple CBC. Problems such as anemia, severe infections, and
some types of cancers can be detected.
Risks to Patient: There are very few risks to the sheep or goat,
providing that the blood is collected under sterile conditions by a trained
Relative Cost: The cost of performing this test is low to moderate.
Normal Ranges: The following chart lists the normal ranges for many of
the common items found on a CBC. Realize that these numbers can vary greatly
between different locations and different laboratories.
|Packed Cell Volume (PCV)
||27 - 45
||22 - 38
|Red Blood Cell (RBC)
||9 - 15
||8 - 18
||240 - 700
||340 - 600
||0.7 - 6.0
||1.2 - 7.2
||2 - 10
||2 - 9
||0 - 1
||0.05 - 0.065
Many of these reference numbers were taken from Duncan JR, Prasse KW: Veterinary
laboratory medicine - clinical pathology, ed 2, Ames, IA, 1986, Iowa State
University Press; and Kramer JW: Normal hematology of cattle, sheep and goats.
In Schlamís veterinary hematology, ed 5, Philadelphia, 2000, Williams
Interpretation of Results:
- Packed Cell Volume (PCV) - This is the total percentage of the blood that
is composed of red blood cells.
Red Blood Cell (RBC) - This is the total number
of red blood cells in one microliter of blood.
- A high PCV occurs most commonly with dehydration and certain heart
- A low PCV can be the result of not enough red blood cells (anemia) or the
occasional state of over-hydration.
Reticulocyte - Reticulocytes are immature red blood cells.
- Low numbers of RBCs (anemia) can be the result of blood loss, inadequate
RBC production in the bone marrow, or actual destruction of the RBCs within
Platelets - Platelets are circulating compounds that help blood to clot.
- High numbers of reticulocytes indicate a regenerative response (i.e. the
bone marrow is producing more red blood cells).
- Low numbers of reticulocytes when anemia is present may indicate a bone
Neutrophils - These are white blood cells (WBC) that are important in
- If low platelet numbers occur, the animal may be prone to bleeding
Band Cells - Band cells are the early stages of a neutrophil.
- High numbers of neutrophils (neutrophilia) occur when the animal is
under stress (shipping), has an infection, or when steroids have been
- Low neutrophil numbers (neutropenia) can occur with very severe
infections, some viral infections, and when there has been long term bone
Lymphocytes - These are WBCs that are part of the immune system.
- The presence of band cells usually indicates that an infection is
occurring in the body. When high numbers of band cells are observed, it is
called a "left shift."
Eosinophils - These are white blood cells that are common in situations
where irritation or inflammation of tissue is found.
- High levels of lymphocytes (lymphocytosis) can occur when the animal has
a chronic infection or lymphocyte leukemia.
- Low lymphocyte numbers (lymphopenia) indicate administration or release
of steroids, viral infections, or stress.
- High numbers of eosinophils indicate a possible parasite problem or an
This section lists only a few of the most common possibilities for cell
changes in a CBC. A physical examination, additional history, and other
tests may be required before a specific diagnosis can be determined.