1. Chapter 12 Additional Hematologic Tests
Hematology Unit 2
Chapter 12
Additional Hematologic Tests
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2. Reticulocytes Immature erythrocytes Polychromatic staining
Supravital stain – New methylene blue – fresh
Not Romanowsky stains
Differing staining methods
Cats – 2 forms of retics
Aggregate – large clumps of
reticulum
Punctate – unique to cats – 2 to 8 small singular basophilic granules
Normal 0.4% aggregate and 1.5% to 10% punctate
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3. Reticulocyte Count
Expression of the percentage of RBCs that are reticulocytes
Percentage per 1000 RBCs
Oil-immersion lens
Done on all anemic animals except horses
Horses do not release retics
Useful in determining bone marrow response
Reticulocyte counts should be interpreted according to the degree of anemia, because fewer mature erythrocytes are present in anemic animals, and reticulocytes are released earlier and persist longer than they do in normal animals. Higher percentages may be seen in hemolytic anemia as compared with hemorrhagic types of anemia.
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4. Corrected Reticulocyte Count
Multiply observed reticulocytes by the observed PCV and then divide by the normal PCV.
Normal – dog 45%; Cat 35%
Example
A dog has a PCV of 15% and observed retic count of 15%
15 × 15/45 ‒ 5%
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5. Reticulocyte Production Index
Another option
Involves the maturation time values
Divide the corrected retic percentage by the maturation time for the observed patient’s PVC (Reticulocyte maturation index) (Table 12-1, page 78)
Example: corrected retic count is 5% and reticulocyte maturation index is 2.5
5/2.5 = 2
which indicates the patient is producing reticulocytes at 2
times the normal rate.
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6. Bone Marrow Evaluation
Valuable tool for diagnosis and prognosis in specific cases
The need for this test is determined by the findings of the differential blood count.
Persistent unexplained pancytopenia, neutropenia, or thrombocytopenia and nonregenerative anemia
Abnormal morphologic changes or unexplained immature cells
Stages neoplastic diseases
Diagnosis parasitic infections – Ehrlichiosis, leishmaniasis
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7. Bone Marrow Evaluation (cont.)
Collection
Aspiration or removal of bone marrow core
Restraint, sedation, or local or general anesthesia
Aseptic technique
Supplies
EDTA prepared syringes
Bone marrow needle
No. 11 scalpel blade
About 12 slides
Sutures (if needed)
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8. Bone Marrow Collection
Aspiration biopsy
Several sites – head of femur or humerus
Aseptic
Rotated and pressure applied – attach syringe and aspirate
Core biopsy
Sometimes better sample quality
Use different sites if done in conjunction with aspiration biopsy
Similar procedure no aspiration – rotate needle to cut piece of bone from the cortex
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9. Preparing Marrow Smears
Multiple slides for various preparation techniques
Must be made immediately if not mixed with EDTA (1 hour with EDTA)
Aspirate sample prepared like blood smears
Line smears, starfish smears, compression smears
Rapidly air-dried
Stain with Romanowsky-type stain
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10. Evaluation of Bone Marrow Films
Systematic approach
Must have differential WBC count from concurrent peripheral blood
Normal
Adult: 50% nucleated cells and 50% fat
Juvenile: 75% nucleated cells to 25% fat
Geriatric: 25% nucleated cells to 75% fat
Acellular – Aplasia
Hypercellular – Hyperplasia
Hypocellular – Hypoplasia
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11. Cells in Bone Marrow
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12. Results M:E ratio Maturation index (left shift index) When present
Stainable iron
Increased mitotic figures
Increased osteoblasts, osteoclasts, and mast cells
Phagocytized material
Metastatic cells
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13. Erythrocyte Sedimentation Rate
The rate RBCs fall in their own plasma will be altered in some disease states
Some automated systems but not common
Manual method
Calibrated tube filled with fresh EDTA-treated blood to the upper calibrated mark
Place in rack – perpendicular to table
Allow to sit undisturbed at room temperature
After 60 minutes (20 in horses), record the level of the top of the RBC column
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14. Erythrocyte Osmotic Fragility
Test of the ability to withstand hemolysis in varying concentrations of saline
Not routinely performed unless in referral centers or research settings
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15. Summary Reticulocyte counts Bone marrow sampling and preparation
Reporting bone marrow results
Erythrocyte sedimentation rate
Erythrocyte osmotic fragility
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