Complete Blood Count
Hematology

Hematology testing represents an important
role of the veterinary technician: to provide
accurate and reliable clinical laboratory test
results to the veterinarian
 A complete hematology profile is indicated for
diagnostic evaluation of disease state, well
animal screening, (e.g. geriatric) and
screening tool before surgery
CBC Include
White and red blood cell counts
 Hemoglobin concentrations
 Packed cell volume (PCV)
 Differential white blood film examination
 Calculation of absolute
values/erythrocyte indices

Types of Cellular Elements

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Red blood cells – Erythrocytes
White blood cells – Leukocytes
Neutrophils
Eosinophils
Basophils
Lymphocytes
Monocytes
Platelets – Thrombocytes (not true cells)
CBC



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Total RBC count
PCV
Plasma protein concentration (TP)
Total WBC
Blood film examination: differential WBC
count, erythrocyte and leukocyte morphology,
platelets estimation.
 Reticulocyte count when the patient is anemic
 Hemoglobin concentration
 Erythrocyte indices
Quality control
Automated analyzers can provide
accurate and cost-effective results.
However, care should be taken in
choosing the most appropriate
instrument a clinic
 Page 32
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Cell counts

Counting of erythrocytes and leukocytes is a
routine part of the CBC. Cells counts can be
performed by manual and automated
methods.
 The total WBC (leukocyte) count is one of the
most useful values determined in a CBC
 Total RBC (erythrocyte) and platelet
(thrombocyte) counts, although are more
difficult and less accurate, may also be
performed manually with a hemocytometer or
by automated methods
Hemocytometer - Unopette

The “Unopette” system is a standardized
method for enumerating leukocytes
using fresh whole blood via a capillary
puncture. This system is made up of the
following components:
[1]
A reservoir that contains a premeasured volume
(1.98mL) of a 3% glacial acetic acid solution.
[2] Self-filling, color coded 20 μL pipet. This pipet is
constructed with one end that fits into the reservoir.
This end is designated as the overflow chamber.
[3] Pipet shield that covers and protects the pipet. The
end of the “shield” is pointed for the purpose of
puncturing the reservoir diaphragm before use.
[4] See Figure 1 for an illustration of the Unopette
system
The Hemacytometer has counting
chambers used to determinate the
number of cells per microliter (µl,
sometimes referred to as cubic
centimeters) of blood.
 Several models are available, but the
most common type used has two
identical sets of fine grids of parallel and
perpendicular etched lines called
Neubauer rulings
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Neubaur system
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http://www.youtube.com/watch?v=89SB1tAa6kg&feature=related
Hematocrit - PCV

In the CBC, we determine the
number of RBC’s in several
different ways. The quickest
and easiest is called the
hematocrit, also referred to as
the packed cell volume (PCV)

PCV / 6 = est RBC count / µL
Plasma Protein Concentration
Plasma Protein (TP)
concentrations estimation by
refractometry is an important
component of the CBC in all
species
 The plasma used to
determinate the PCV is
collected by breaking the
hematocrit tube just above the
Buffy coat- plasma interface

Hemoglobin (Hgb)

Hemoglobin counts are
usually done with an
automated analyzer. The
analyzer will mix a small
amount blood with a solution
to lyse the cells. It will then
compare the color of the
lysed cells to the normal
Hematology values
Erythrocyte Indices

Determination of erythrocyte indices is helpful
in the classification of certain types of anemia
 The erythrocyte indices include: the mean
corpuscular volume (MCV), mean corpuscular
hemoglobin (MCH) and MCH concentration
mean corpuscular hemoglobin concentration
(MCHC).
 The indices can provide an objective measure
of the size of the RBCs and their average
hemoglobin concentartion.
Mean corpuscular volume (MCV) :

The MCV expresses the average volume (or
size) of the individual erythrocyte. Using the
total erythrocyte count, hemoglobin content
and packed cell volume, it is possible to
calculate the volume of an average erythrocyte
and it’s hemoglobin concentration. Dividing
the packed cell volume by the RBC
concentration and multiplying by 10
determines the MCV.
Mean corpuscular hemoglobin
concentration (MCHC)
The MCHC is the concentration of
hemoglobin in the average erythrocyte,
or the ratio of weight of hemoglobin to
the volume in which it is contained.
 The MCHC is calculated by dividing the
hemoglobin concentration by the PCV
(%) and multiplying by 100.

Mean corpuscular hemoglobin
(MCH)

MCH is the weight of hemoglobin
contained in the average erythrocyte.
The MCH is calculated by dividing the
hemoglobin concentration by the RBC
concentration and multiplying by 10.
Blood films

Remember ! The blood film is used to
perform the differential WBC count;
estimate platelet numbers; and evaluate
the morphological features of WBCs,
RBCs and platelets.
Performing the Differential Cell
Count

This is where the different white blood cells
are tallied separately. This can be done by a
blood counting machine, or by hand.
 To manually count the different cells, first you
must make a perfect slide. Stain the slide
once it is dry.
 Using a cell counter you will tally a total of 100
cells (this will make it easy to turn the numbers
into a %)
The percentages will aid in initial
diagnoses, interpretation should be
based on the absolute numbers of the
various cells.
 Absolute numbers are obtained by
multiplying the percentage by the total
leukocyte count

Because 100 WBC are counted , the
number of each WBC type observed is
recorded as a percentage.
 This is called the relative WBC count
 Various counting devices are available to
help perform the differential WBC
 Page 44
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