3. White Blood Cells
• Five major White Blood Cells
• Further defined into two groups:
1. Granulocytes
• Neutrophils
• Eosinophils
• Basophils
2. Monocellular cells (agranulocytes)
• Lymphocytes
• Monocytes
4. White Blood Cells
• Granulocytes:
• Classified due to the granules present in their cytoplasm
• Monocellular cells (agranulocytes):
• Classified due to their round globular shaped nucleus
** somewhat misleading due to the fact that most monocytes do not
have a round nucleus**
5. Granulocytes
• Neutrophils (segmented neutrophils, segs)
• Most predominant WBC in healthy animals
• First line of defense against infections
• 1 ½ times the size of RBC’s
• Function:
• Seek out, ingesting, killing, and invading
microorganisms
8. Granulocytes
• Eosinophils
• Second most common granulocyte
• Slightly larger than neutrophils
• Function:
• Hypersensitivity reactions
• Parasitic infections
• Allergic reactions
9. Eosinophils
Morphology:
• Canine: variable in size, round-oval in shape.
The cytoplasm is faint blue/pink that contains
round pink-orange granules, lobed nuclei with
condensed chromatin (less lobed than
neutrophils)
10. Eosinophils
Morphology:
• Feline: uniform in size and shape. The cytoplasm
is faint blue/pink that contains rod shaped pink-
lavender granules, lobed nuclei with condensed
chromatin (less lobed than neutrophils)
11. Eosinophils
• A specific morphologic variant of the eosinophil is
seen in greyhounds and other sighthounds
• Lack visible granules and appear as cells with
slightly segmented nuclei, grey/lavender
cytoplasm, and vacuoles.
12. Granulocytes
• Basophils
• Occasionally observed/difficult to find
• Slt larger than neutrophils
• Commonly mistaken for monocytes
• Function:
• Hypersensitivity reactions
• Parasitic infections
• Allergic reactions
13. Basophils
Morphology:
• Nucleus is segmented with dense chromatin
• Can also commonly have a kidney bean shaped nucleus
• Cytoplasm is pale blue/grey/lavender
• Contains a few distinct dark blue/purple granules
• Distinct “cobblestone” appearance
• Cytoplasm MAY contain small vacuoles
• Most commonly confused with monocytes
15. Monocellular cells
• Lymphocytes
• Second most common WBC seen
• Slightly larger than red blood cells
• Commonly confused with nRBC
• Function:
• Antibody immunity
• Cell mediated immunity
16. Lymphocytes
Morphology:
• Small amount of light blue cytoplasm
• Coarsely clumped chromatin
• takes up the majority of the cell
• Nucleus is round-oval in shape
• may be slightly indented
20. Monocytes
Morphology:
• Variable in shape from round to angular
• Grey/blue cytoplasm
• Nucleus is irregular and variable in shape
• and has a lacey less dense chromatin pattern
• May have a few small vacuoles
(not distinguishing factor)*
23. Immature WBC
Left shift
• Increased numbers of immature neutrophils
• Most common cause is inflammation
• Can also be seen in some marrow disorders
(leukemia) or severe bone marrow injury
• Cells are classified based
on their stage of maturation
24. Immature WBC (neutrophils)
• Shape of the nucleus differentiates these cells
• Myelocyte – nucleus appears round
• Metamylocyte – kidney bean shape
• Band cell- horseshoe shape
• Mature cell – segmented
25. Immature WBC
• Band cells
• Widths of the nuclear margins
are smooth and parallel
26. Toxic changes
• Hypersegmentation
• Neutrophil with 5 or more lobes
• Causes:
• Common ageing artifact
• Exposure to excessive amounts of EDTA
• Also seen in:
• Glucocorticoid therapy
• Hyperadrenocorticism
• Chronic infections
27. Toxic Changes
Toxic Neutrophils
• Occurs when the maturation in the bone marrow is
accelerated
• Often accompanied by a left shift
• Causes:
• Inflammation
• Graded as mild, moderate and severe
• Severity of abnormalities and number of cells affected
• We evaluate five main features to determine toxicity…
28. Toxic changes
1. Cytoplasmic basophillia - cytoplasm develops a
streaky irregular darker blue appearance
2. Presence of dohle bodies
3. Cytoplasmic vacuolation - vacuoles are present within
the cytoplasm of the cell giving it a frothy appearance
• Vacuolation can also be a storage related artifact
4. Nuclear immaturity - nuclear chromatin is lighter, finer
and less clumped than that of normal cells
• often subtle and difficult to visualize
5. Toxic granules – distinct fine granules in the cytoplasm
• change is not common and can be difficult to visualize
29. Toxic Changes (Neutrophil)
A: Normally matured
segmented
C: late band neutrophil
Both: white cytoplasm
with pink granules
long and fairly narrow
nuclei
tightly condensed
chromatin
B: Segmented
D: Band neutrophil
Both: with toxic changes
Nucleus is larger
less condensed chromatin
bluer cytoplasm due to
retention of ribosomal
RNA
30. Toxic Changes
Reactive Lymphocytes
• Large lymphocytes
• Seen in:
• Antigenic stimulation
• Relatively non-specific finding
• Any disease process can cause an antigenic
stimulation leading to the presence of these cells
in circulation
31. Toxic Changes
Reactive Lymphocytes
• Extremely variable in size and morphologic features
• Chromatin is coarsely clumped
• Nucleus is extremely variable in shape
• Can have an increased amount of cytoplasm
• Cytoplasm stains deep blue/purple
32. Toxic Changes
Granular lymphocytes
• Usually found in low numbers in healthy animals
• Caused by chronic antigenic stimulation
• Distinguished by the presence of distinct pink
granules collected into one area of the cytoplasm
33. Abnormal WBC
• Mast cells
• Rarely seen in peripheral blood smears
• Large irregular deeply staining
• Round/oval nucleus difficult to visualize
• Large amounts of deep blue cytoplasm
• Numerous small purple cytoplasmic granules
• Seen in:
• Inflammatory diseases
• Certain neoplastic diseases
34. Abnormal WBC
• Smudge Cells or Blast cells
• Dying WBC’s
• Normal to see an occasional cell
• Increased numbers are indicative of leukemia
• May be an artifact of slide preparation
• By applying too much pressure to the slide
35. Abnormal WBC
• Pelger-huet anomaly
• Congenital disorder in dogs
• All the granulocyte nuclei fail to undergo segmentation
• Can also occur in certain drug interactions
Morphology:
• Nucleus is uniform
• Lacks the toxic changes
• distinguishes this from an inflammatory process
• Accompanied by a normal leukogram
• Neutrophils have a normal function
37. WBC Inclusions
• Usually include or represent phagocytosed
material such as other cells, cell debris,
retained cellular material and infectious
organisms
38. WBC Inclusions
• Chediak Higashi Syndrome
• Syndrome of cats (Persians)
• Neutrophillic inclusion
• Variable size
• Round, pale blue/pink
• Attaches to granules in cytoplasm
• Usually see 1:3 ratio
• Tend to have lower platelet numbers
• Otherwise healthy
39. WBC Inclusions
• Barr body
• Found in neutrophils
• Appendage attached to nucleus
• Small tennis racket shape
• No pathological significance
• Indicates that the dog is female
40. WBC Inclusions
• Dohle Body
• Small irregular pale blue aggregate
• Present in cytoplasm of neutrophils
• Represents aggregates of the rough
endoplasmic reticulum
• Seen in toxic changes
41. WBC Inclusion
• Distemper virus
• Aggregates of viral particles
• Round and variable in size
• Pink/lavender in color
• Found in RBC,WBC
• Rarely seen even with + infection
42. WBC Parasites
• There are several organisms that can be
detected from examination of a peripheral
blood smear, however they can be
intermittently seen and therefor further
serological testing should be done
• Transmission most commonly occur
through the bites of ticks
43. WBC Parasites
Hepatozoon canis
• Protozoal parasite transmitted via ticks
• Not commonly seen even with active infection
• Accompanied by a severe leukocytosis
• Found in a small number if cells
Morphology:
• Large aqua-staining rod
• Esinophilic patches
• May distort the cell border
• also be seen as a clear capsule
45. WBC Parasites
Ehrlichia ewingli and Ehrlichia canis
• Bacterial parasite transmitted via ticks
• More commonly seen in the south
• Dogs can be asymptomatic or present with a
fever and polyarthritis
• Accompanied by moderate leukopenia and
severe thrombocytopenia
• Rarely seen on direct smear
• Is a zoonotic dz
46. Ehrlichia spp.
Mporohology:
• E. ewingli morula – found in neutrophils
• E. canis – found in lymphocytes and monocytes
• Both appear as medium well defined round-oval
inclusions within the cytoplasm that stain deep blue/purple
48. WBC Parasites
Anaplasma phagocytophilum
• Tick-born bacterial parasite
• Accompanied by a mild to moderate
nonregenerative anemia and thrombocytopenia
• Not commonly seen even with a positive infection
• Is a zoonotic disease
49. Anaplasma phagocytophilum
• Morphology:
• Small deep blue/purple structures
• Grouped individually or in grape-like clusters
• Observed in cytoplasm of circulating neutrophils and
rarely in eosinophils
51. Thrombocytes
• 1’st line of defense for the normal function of clotting
• (aka: hemostasis)
• Formed and released from the bone marrow
• Lifespan in the blood is 5-10 days
• Observed/counted in counting area of the blood smear
• Scan feathered edge of the smear to observe for clumps
52. Thrombocytes
Morphology
• Lack a nucleus
• Vary greatly in size, shape, and granularity
• Often have fuzzy edges
• Can have string-like projections arising from the
body of the cell
• Stain pale lavender to dark purple
53. Thrombocytes
Normal morphology: Dog
• Round, discoid, oval, elongated, or flat
• Some appear granular
• Containing few purple/blue granules
surrounded by a pale blue matrix
54. Thrombocytes
Morphology: Cat
• Morphologically similar to the dog
• Spherical or elongated
• Tendency to clump
• More variable in size
• May be as large as the red blood cells
• considered normal
55. Thrombocyte Abnormalities
• 90% of bleeding disorders in dogs and cats
results from abnormalities with either platelet
numbers or platelet function
• Greyhounds tend to have a lower number of
platelets overall
57. Thrombocyte Abnormalities
Clumping
• Causes:
1. Sample collection (slow venipuncture)
2. Age of the sample
(samples over 24 hours are prone to clumping)
3. Common in cats but is normal
• The feathered edge should be
scanned first to observe for this
abnormality, the clumps being
heavier tend to be pushed to the
edge of the smear
59. Thrombocyte Abnormalities
Mega platelets or megathrombocytes
• Large platelets
• Can be an indication of an early production and
release
• May be as large as the RBC’s
• Can be a normal in cats
61. Platelet disorders
Quantitative abnormality
• Thrombocytopenia:
• Decreased number of platelets
• Normal function
• Caused by:
• Increased utilization of platelets
• Increased destruction of platelets
• Decreased production
62. Platelet disorders
Qualitative abnormalities:
• Numbers are normal but the function is compromised
• Hereditary function defect
• Ex: von wilebrans disease and hemophelia
• Very rare defect
• Usually accompanied by and anemia and/or neutropenia
• Other causes:
• Cancer, immune or infectious etiologies, NSAID’s
63. Platelet disorders
Thrombocytosis:
• Increase in the number of platelets
• Very rare, usually secondary to another problem
• Causes:
• Iron deficiency’s anemia, certain inflammatory conditions,
severe trauma (fractures), certain drug therapies,
neoplasia, certain gastrointestinal diseases
• Transient thrombocytopenia caused by excessive
exercise or epinephrine injections
