Transcript Blood Cell Differentials

Let’s Review:
Blood Composition

Separates into three
components:
› Red Blood Cells (RBC’s)
› White Blood Cells and platelets
(buffy coat)
› Plasma

Bottom 1/3 to ½ of tube
contains the heaviest of cellular
material (the RBC’s).
The blood film is used to perform the
differential WBC count; estimate platelet
numbers; and evaluate the
morphological features of WBCs, RBCs
and platelets.
 Wedge smears are prepared by placing
a small drop of blood on a clean glass
microscope slide

Always stain using the lightest to darkest
stain.
 Remember which side of your slide is up
(clothes pins are marked “top”)
 Rinse off from back side of slide
 May heat fix to speed up process.

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 %)
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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).
The hematocrit or the
packed cell volume will
tell you if the animal is
dehydrated or anemic.

Whole blood is collected in
an anticoagulant, such as
EDTA or heparin and place
in a capillary tube (75
mm). Microhematocrit
tubes should be filled, with
one ended plugged with
clay sealant
A blood sample is placed in
a tiny glass tube and spun in
a centrifuge for 2-5 minutes.
 Lie the tube in the
centrifuge Hct head with
plugged end to the outside,
note the number of your
slot. Ensure that a balancing
hematocrit tube is placed
opposite, either by
someone placing their tube
there, or by adding an
empty tube
 The cells are heavier than
the plasma and are
compacted at one end of
the tube.
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Special hematocrit tube have a linear scale, so
the amount of blood in the tube need to be
exact
The bottom of the RBC layer should be at the
zero line and the top of the plasma on the top
line (page 37 Fig 2-7)
PCV is determined as the percentage of the
cellular portion relative to the total amount of
blood in the tube
Plasma color and
transparency may be
helpful in the
determination of a
diagnosis and should be
recorded
 Normal plasma is clear
and a pale straw –yellow
color
 Page 36

Plasma Protein concentrations
estimation by refractometry is
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

The plasma is allowed to flow onto the
refractometer prism.
 Page 37 fig 2-9


Literally means “no
blood” but clinically
means low total blood
hemoglobin.

Absolute anemia: most
common, caused by
failure to produce
adequate numbers of
cells or by a loss of cells at
a rate greater than can
be produced.
Anemia
Clinical Signs of Anemia
Pale mucous membranes
 Exercise intolerance
 Tachycardia
 Panting
 Icterus if anemia is caused by RBC
breakdown in bloodstream.

Classification of Anemia

By RBC size (MCV):
› Macrocytic
 Erythrocytes are larger than normal.
 Usually in the presence of regenerative anemia.
 May be seen in FeLv
 May see anisocytosis
› Normocytic
› Microcytic
 Cells are smaller than normal which has been determined by Mean Cell
Volume (MCV).
 Usually occurs with iron deficiency caused by chronic blood loss or
parasitism

By Hemoglobin concentration (MCHC)
› Hypochromatic
 RBC’s have decreased density of the characteristic hemoglobin color.
 Frequently observed in iron deficiency caused by chronic blood loss or
parasitism.
› Normochromatic
Classification According to
Bone Marrow Response

Regenerative anemia:
› Characterized by evidence of increased
production and delivery of new
erythrocytes into circulation.
› Usually suggests an extra bone marrow
cause (blood loss, hemolysis, etc.).,
› Diagnosis:
 Peripheral blood smear.
 Will see macrocytosis, polychromasia with
Wright’s stain, reticulocytosis with methylene
blue stain, may also see increased numbers
of nucleated RBC’s

Nonregenerative anemia:
› Indicates anemia is result of bone marrow
defect.
› No response evident in peripheral blood.
› Marrow examination may be helpful with the
diagnosis.
Types of Anemia

Blood Loss Anemia
› Results from excessive hemorrhage although source
can be subtle.
› Must determine if blood loss is internal or external.
› Possible causes:
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Trauma
Persistent bleeding lesions
Thrombocytopenia
Coagulopathies
Heavy parasitism
Iatrogenic causes

Acute Blood Loss
› Anemia due to loss of blood in a sudden episode.
› All RBC parameters are normal for the first 12 hours.
› Hypovolemic shock can be apparent prior to a
decreased PCV.
› Anemia will be normocytic, normochromatic, and
apparently unresponsive with a low CRC.
› By day 4-5, the retic count increases and the anemia
appears responsive.
Chronic Blood Loss
Blood is lost slowly and continuously for a period of time.
 Body compensates for anemia by lowering oxygenhemoglobin affinity, preferential shunting of blood to
vital organs, increased cardiac output (tachycardia),
and increased levels of erythropoietin.
 Anemia remains unresponsive unless iron stores are
depleted.
 With decreasing iron stores, erythropoiesis is limited and
RBC’s become smaller and deficient in Hgb (microcytic
and hypochromic).
 Clinical signs include lethargy, weakness, decrease
exercise tolerance, anorexia, pallor, lack of grooming,
mild systolic murmur.
 Results in iron deficiency

Hemolytic Anemias
Result of increased erythrocyte
destruction within the body.
 Intravascular hemolysis: desctruction of
erythrocyctes within the blood vessels
and loss of Hgb from the cells.
 Extravascular hemolysis: RBC’s are lysed
following phagocytosis.

Blood Borne Parasites
Can produce anemia through hemolysis
 Parasites attach to erythrocyte
membrane and cause increased
destruction of the cells.
 May have symptoms of non-specific
weight loss, anorexia, fever, etc.
 Babesia
 Ehrlichiosis

Toxin Induced Anemia/Heinz
Body
Hemoglobin denatures and forms Heinz
bodies.
 Onion toxicity, Acetaminophen toxicity

Von Willebrand’s
Disease
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Canine vWD is the most
common inherited blood
disorder.
Von Willebrand’s Factor
promotes platelet clumping
in healthy dogs. Lack of this
factor will cause a bleeding
disorder.
Dobies, German Sheperds,
and Labs most common.