1. Red Blood Cells
Erythrocytes (RBC’s)

2. Formed Elements (Cells) of Blood
Red blood cells (erythrocytes)
White blood cells (leukocytes)
Granular leukocytes
Agranular leukocytes
Platelets (special cell fragments)

3. Complete Blood Count (CBC)
Definition – series of tests performed on whole blood, looking at the 3 types of blood cells
White blood count & differential white count (“WBC & Diff”)
RBC indices
Hemoglobin
Packed cell volume (PCV)
RBC morphology
Platelet evaluation

4. CBC Equipment

5. Hemograms A written record of the CBC Includes the following:
RBC indices
WBC indices
Platelet evaluation
General Comments on any unusual findings

6. Erythrocytes

7. Erythrocyte Terminology
Erythrocyte function
Erythron
Erythrocyte (RBC)
Polycythemia
Anemia
Regenerative
Degenerative

8. Laboratory Tests Used to Evaluate the Erythron
Packed Cell Volume (PCV)
Hemoglobin (Hg or Hb)
RBC Count
Mean Corpuscular Values
Erythrocyte Sedimentation Rate (ESR)

9. Packed Cell Volume (PCV)
Also known as “Hematocrit” (Hct)
Definition – the % of whole blood composed of RBC’s
Most frequently used erythrocyte test

11. Packed Cell Volume (Hematocrit)
Centrifuging blood forces formed elements to separate from plasma
PCV is % of total volume that is RBC’s

16. Anatomy of a PCV Tube Clay or wax plug RBC’s Buffy Coat
Heaviest specific gravity of cells
Sinks to bottom after centrifuge
Thickest layer
Buffy Coat
Thin white layer…… What is in this layer?
Plasma – usually yellow
NOT serum…… Why?

19. Anatomy of a PCV Tube

21. Hematology Reference Ranges

22. Normal PCV Values Hematology Reference Ranges (Hendrix) Horse? 
Dog = 37-55% [mean = 45]
Cat = 30-45% [mean = 37]
Horse? 
Other RBC Indices in this Appendix A
RBC (Red Blood Count)
Hemoglobin
Mean Corpuscular Values

23. Influences on PCV Physiological (non-disease) Pathological (disease)
High altitude……. Polycythemia Why?
Excitement increases PCV [horses especially] Why?
Excessive IV fluids decreases PCV [Hemodilution – more plasma]
Pathological (disease)
Dehydration [Hemoconcentration – less plasma]
Anemia decreases PCV (less RBC’s)

24. Hemoglobin Testing What is hemoglobin? Function of hemoglobin
Hemoglobinometer – Refractometer used to obtain hemoglobin concentration
Formula for rough estimate of hemoglobin
Hb = PCV/3
results in grams per decaliter (g/dl)
Average canine hemoglobin = g/dl

25. Use of Refractometer

28. RBC Count Use of hemocytometer Use of electronic cell counters
Technique the same as for WBC Count, except dilution factors and counting areas
As much as a 20% error!!!
Use of electronic cell counters
More accurate than hemocytometers
Formula for rough estimate of RBC Count
RBC Count = PCV/6
results in millions per microliter

30. Erythrocyte Indices Also known as Mean Corpuscular Values
Definition – A look at the average (mean) RBC size, hemoglobin, and hemoglobin concentration
Calculated by referral labs and reported on lab reports sent to veterinary hospital
Used by DVM to help in diagnosing type of anemia present

31. 3 Erythrocyte Indices Mean Corpuscular Volume (MCV)
SIZE of the average RBC
Helpful in determining what type of anemia might be present
Mean Corpuscular Hemoglobin (MCH)
Average WEIGHT of hemoglobin in the average RBC
Not very helpful
Mean Corpuscular Hemoglobin Concentration (MCHC)
Average CONCENTRATION of hemoglobin in the average RBC

32. Erythrocyte Sedimentation Rate (ESR)
Measures rate at which RBC’s separate from their plasma in a column of whole blood (that has anticoagulant)
How fast RBC’s fall in a vertical tube over a given period of time
Wintrobe Hematocrit Tube
Used for prognosis, not diagnosis
Not used too often in veterinary medicine

33. Interpretation of ESR
Horses – RBC’s tend to stack up in a “stacked coin” arrangement (Rouleaux Formation)
Increased ESR
Anemia – little traffic in the Tube
Increased PCV – bumper to bumper traffic in rush hour
Decreased ESR

36. Erythrocyte Morphology
Normal Morphology
Size abnormalities
Shape abnormalities
Color abnormalities
RBC Inclusions

37. Normal Erythrocyte Morphology
Most common of blood cells on a blood smear
Biconcave disc
No nuclei in mammal RBC’s
Nuclei present normally in bird and reptile blood
Normal canine RBC’s have a central pallor (lightness) to them

39. Erythrocytes on a Needle

40. RBC Size & Pigment Normocytic Macrocytic Microcytic Normochromic
Hypochromic
No such thing as “Hyperchromic”
Why?

42. Erythrocyte Size Abnormalities
Record abnormal findings under “General Comments” on the hemogram
Anisocytosis
Macrocytes
Microcytes
Normocytic

45. Erythrocyte Shape Abnormalities (Poikilocytosis)
Schistocytes
Acanthocytes
Crenation (Echinocytes)
Keratocytes
Spherocytes
Target Cells (Codocytes)

46. Erythrocyte Shape Abnormalities
Poikilocytosis – general term for shape abnormalities

49. Schistocytes
RBC fragments

50. Acanthocytes (Spur cells)
Unevenly distributed surface projections of different lengths

52. Crenation
Echinocytes (Burr cells) – spiculated (pointed) cells with short, evenly spaced surface projections
Artifact? – slow drying of blood films
Feline blood

53. Crenation (Echinocytes)

54. Keratocytes
Helmet cells – contain a vacuole?

55. Spherocytes Darkly staining RBC’s with no central pallor Canine only?
Autoimmune hemolytic anemia

56. Target Cells (Codocytes)
RBCs with central rounded area of hemoglobin surrounded by clear zone
A few in normal blood?
Associated with anemias

57. Target Cells

58. Erythrocyte Color Abnormalities
Normochromic
Polychromasia – polychromatophilic RBCs
Blue tint to cytoplasm, due to presence of organelles remaining in cytoplasm (young cells)
Hypochromic – decreased staining due to insufficient hemoglobin in cells Hyperchromic (no such thing!)

60. Nucleated RBCs (NRBCs)
RBC Inclusions
Reticulocytes
Basophilic Stippling
Howell-Jolly Bodies
Heinz Bodies
Nucleated RBCs (NRBCs)

61. Reticulocytes Immature RBCs that contain organelles (ribosomes)
As cell matures they are lost
Account for diffuse blue-gray stain with Wright’s stain
1% in normal circulation
Special stains needed usually

63. Basophilic Stippling Presence of small, dark-blue bodies all over RBC
Represents residual RNA
Common in immature RBCs

65. Howell-Jolly Bodies Basophilic nuclear remnants
Seen in young RBCs in response to anemia
Phagocytes in spleen remove these remnants

67. Heinz Bodies Rounded structures representing denatured hemoglobin
Pale or blue area, depending on stain
Cause: certain oxidants or drugs
Normal cats may have them

68. Heinz Bodies

72. Nucleated RBCs (NRBCs)
Also called metarubricytes
Represent early release of immature cells during anemia
If > than 5 per 100 WBC’s
Correct WBC Count
Normal in bird & reptile blood

74. NRBC’s – How Many Do You See?