Means of Evaluating Leukocytes Flashcards
What methods can be used to get a WBC count?
Manual diluting techniques can be used along with a hemacytometer, or an automatic cell counter can be used.
What is the margin of error when manually counting with a hemacytometer?
20% even with excellent technical skills
What factors can affect the WBC count?
All neutleated cells are counted - including NRBCs.
How can NRBCs be accounted for when using an automatic cell counter?
Count the number of NRBCs/100 WBCs on a blood smear, then corrected WBC count = initial WBC x 100 / (100+ NRBCs)
Define leukocytosis.
A white blood cell count greater then the upper normal values for species.
What is the usual cause of leukoytosis?
neutrophilia
Define leukopenia.
a WBC count less then the lower normal values for the species
Why does a leukopenia equate to a neutropenia?
lymphocytopenia and eosinopenia can’t cause a leukopenia if the nutrophil count is normal
What attributes are evaluated on a peripheral blood smear?
RBC rouleaux, RBC agglutination, platelet aggregation, relative number of leukocytes, examine RBC morphology, conduct differental WBC count, examine WBC morphology, estimate adequacy of platelet number and evaluate their morphology
What is normal segmented neutrophil morphology?
narrowing between nuclear lobes, cytoplasm pale pink
What is normal band neutrophil morphology?
nuclear membrane is smooth without indentations and has parallel sides
Define left shift.
a significant number of band neutrophils seen in peripheral blood smear
What is the cause of toxic neutrophils?
toxemia
What morphological features are seen in toxic neutrophils?
Doehle bodies, cytoplasmic basophillia/vacuolization, and/or prominent cytoplasmic granules
What do Doehle bodies indicate?
mild toxic change
What does cytoplasmic basophilia/vaculoziation indicate?
moderate toxic change
What do prominent cytoplasmic granules indicate?
severe toxic change
What does hypersegmentation indicate?
prolonged blood transit time
What conditions can cause prolonged blood transit time?
c-steroid administration, Cushing’s, late stages of chronic inflammitory disease
How is a hypersegmented neutrophil distingushed from a segmented neutrophil?
4 or more distinct nuclear lobes are present (5 in the horse)
What criteria are used to identify monocytes?
large elongated or trilobed nucleus, grey blue cytoplasm, cytoplasm
How are macrophages distinguished from monocytes?
rarely seen - macrophages are very large with granular vacuolated cytoplasm
What are some conditions that might cause the presence of macrophages?
erlichia, histoplasmosis
What is normal dog eosinophil morphology?
granules are variable in size, shape, number, may be vacuolated. Stains dull orange and does not fill cytoplasm of cell.
What is normal cat eosinophil morphology?
very small elliptical or rod shaped granules, fills cytoplasm of cell and stains dull orange
What is normal cow eosinophil morphology?
small, round granules which fill the cell cytoplasm and stain bright orange
What is normal horse eosinophil morphology?
large round brilliant orange granules
What is normal non-mammalian eosinophil morphology?
granules don’t stain and appear greenish
What is normal canine basophil morphology?
granular purple cell, sparse in peripheral blood
What is normal cat basophil morphology?
no granules seen, larger then segmented neutrophil, greyish cytoplasm
What is normal cow/horse basophil morphology?
numerous purple granules
What is normal dog lymphocyte morphology?
usually small with small amounts of blue cytoplasm, round nucleus
What is normal cat lymphocyte morphology?
simialar to the dog; the nucleus is occasionally slightly indented
What is normal cow lymphocyte morphology?
small lymphocytes are similar to those of the dog, larger lymphocytes have more abundant cytoplasm and indented nuclei
What is normal horse lymphocyte morphology?
similar to the dog
How is a differential leukocyte count performed?
leukocytes on a stained smear are identified until 100 cells classified, # of NRBCs also counted, the percent of each type multiplied by the WBC count which gives the number of each per microliter of blood
Define absolute number.
number of cells/mcL of blood
What is the normal
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