Basics of Reading Blood Test Results: CBC (Complete Blood Count)

Introduction

• Focus on small animals: cats and dogs.
• CBC (Complete Blood Count) or Haematology Report focuses on blood cells.
• Excludes serum biochemistry (proteins and electrolytes).

Components of CBC

Red Blood Cells (RBCs) or Erythrocytes

• Haemoglobin (Hb):

  • Amount of haemoglobin per litre of blood.
  • Indicator of blood's oxygen-carrying capacity.

• Packed Cell Volume (PCV) or Hematocrit (HCT):

  • Proportion of blood made up of RBCs.

• Number of RBCs:

  • RBC count per unit volume.

• MCV (Mean Corpuscular Volume):

  • Size of erythrocytes.

• MCHC (Mean Corpuscular Hemoglobin Concentration):

  • Color of erythrocytes.

• Reticulocytes:

  • Immature RBCs; increase during high RBC production.

Conditions

• Erythrocytosis or Polycythemia:

  • High RBCs, possibly due to dehydration (relative erythrocytosis) or physiological/disease causes.

• Anemia:

  • Low RBCs, haemoglobin, and PCV.
  • Causes: increased destruction, loss (bleeding), or decreased production.

• Cell Characteristics:

  • Normochromic: Normal color.
  • Hypochromic: Less color.
  • Hyperchromic: More color.
  • Normocytic: Normal size.
  • Microcytic: Small size.
  • Macrocytic: Large size.

White Blood Cells (WBCs) or Leukocytes

• Leukocytosis: Increase in WBCs.
• Leukopenia: Decrease in WBCs.

Types of Leukocytes

• Neutrophils:

  • Neutrophilia: Increase, due to stress, inflammation, corticosteroids.
  • Neutropenia: Decrease, due to severe inflammation, decreased production.
  • Bands & Segmented Neutrophils: Indicators of cell maturity.

• Lymphocytes:

  • Lymphocytosis: Increase, due to chronic inflammation, stress.
  • Lymphopenia: Decrease, often stress-related.

• Monocytes:

  • Monocytosis: Increase, indicates chronic inflammation or stress.
  • Monocytopenia: Usually not clinically significant.

• Eosinophils:

  • Eosinophilia: Increase, due to allergies, hypersensitivity, parasites.
  • Eosinopenia: Can be normal, stress-related.

• Basophils:

  • Rare, related to allergic reactions.

Stress Leukogram

• Pattern indicating stress or corticosteroid response:
  • Mature neutrophilia.
  • Lymphopenia.
  • Eosinopenia.
  • Monocytosis.

Example Analysis

• Normocytic Normochromic Anemia:

  • Low RBCs, normal MCV and MCHC.
  • Could be non-regenerative or pre-regenerative anemia.

• Leukocytosis:

  • Due to mature neutrophilia.

Conclusion

• Understanding CBC results helps in clinical settings.
• Knowing terminology and conditions aids in discussions with veterinarians.
• Potential for a veterinary basics series to aid learning.

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Additional Resources

• Mentioned additional resources for further study.

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