Veterinary Hematology: Erythrocyte Morphology, Kinetics, and Pathology

Vocabulary practice flashcards covering erythrocyte production, maturation, morphology, breakdown, and abnormal cellular findings in veterinary hematology.

Reticuloendothelial System (RES)

A branch of the immune system consisting of macrophages located in the liver and spleen that breaks down and clears old cells, abnormal cells, bacteria, and cellular debris from the blood.

Hemoglobin Degradation

The breakdown process in which hemoglobin splits into globin (which is reused), iron (which is reused), and heme (which is converted into unconjugated bilirubin and transported bound to albumin to the liver).

Icterus (Jaundice)

A condition characterized by yellowing of tissues resulting from an elevated concentration of bilirubin circulating in the bloodstream.

Rubriblast Kinetics

The red blood cell precursor cell from which a single rubriblast produces $16$ mature erythrocytes over an approximate $5\text{ day}$ production timeline before release into circulation.

Rubricyte

The developmental stage of nucleated erythroid precursors at which cellular mitosis ceases.

Erythrocyte Maturation Sequence

The sequential order of red blood cell maturation: rubriblast $\rightarrow$ prorubricyte $\rightarrow$ rubricyte $\rightarrow$ metarubricyte $\rightarrow$ polychromatophil (reticulocyte) $\rightarrow$ mature RBC (erythrocyte).

Morphological Changes During Erythropoiesis

The structural progression wherein cytoplasm transitions from blue to orange due to RNA depletion and hemoglobin accumulation, while the nucleus condenses with aggregated chromatin and is eventually extruded.

Packed Cell Volume (PCV) Normal Values

Normal reference intervals for adult animals: dogs $37\text{--}55\%$ (~the 40's), cats $30\text{--}45\%$ (~the 30's), horses $27\text{--}43\%$ (~the 30's), and cows $24\text{--}46\%$.

Agglutination

The irregular clumping of red blood cells in the monolayer caused by antibodies binding to surface antigens on RBCs, characteristically observed in immune-mediated hemolytic anemia (IMHA).

Rouleaux

The organized stacking of red blood cells resembling columns of coins; physiologically normal in horses, absent in healthy dogs, and increased in dogs and cats during states of inflammation or neoplasia.

Agglutination vs. Rouleaux Distribution

Two distinct arrangements of red blood cells on a blood smear: agglutination presents as disorganized clusters driven by immune-mediated antibody crosslinking, whereas rouleaux presents as organized, linear coin-like stacks.

Saline Dilution Test

A wet preparation test performed by adding a drop of saline to fresh blood to differentiate cell patterns: rouleaux will disperse, whereas agglutination will persist.

Mean Corpuscular Volume (MCV) Categories

The diagnostic classification of red blood cell volume: normocytic denotes normal cell volume, macrocytic denotes higher than normal volume, and microcytic denotes smaller than normal volume.

Macrocytic Anemia

An anemia characterized by larger than normal RBCs, typically indicating a responsive or regenerative bone marrow response because immature red blood cells are larger than mature erythrocytes.

Anisocytosis

Variation in the size of red blood cells in a blood sample; physiologically normal in cows, and elevated in regenerative anemias due to younger, larger cells circulating.

Polychromasia

Variation in RBC staining coloration ranging from blue to red; immature cells exhibit basophilia due to residual RNA and endoplasmic reticulum, frequently seen in regenerative anemia.

Polychromatophil

An immature, non-nucleated erythrocyte that stains slightly basophilic or purple on standard blood smears; recognized as a reticulocyte when stained with new methylene blue (NMB).

Hypochromia

Erythrocytes characterized by an abnormally large central pale area resulting from decreased intracellular hemoglobin, typically caused by iron deficiency or chronic blood loss.

Avian Erythrocytes

Mature red blood cells found in birds that are characteristically oval in shape and retain their cell nucleus.

Schistocytes (Schizocytes)

Irregular fragments of red blood cells caused by mechanical trauma in the circulation (such as shearing against intravascular fibrin strands); associated with DIC, vascular neoplasms, and iron deficiency.

Acanthocytes (Spur Cells)

Red blood cells displaying two or more uneven, sharply pointed bent spicules; associated with liver disease, hemangiosarcoma, and hyperlipidosis (such as hepatic lipidosis), or occurring as artifacts.

Echinocytes (Crenated Red Blood Cells)

Erythrocytes with multiple uniform, evenly spaced surface projections; frequently an artifact of slow drying, excess EDTA, improper smear preparation, or old blood, but clinically associated with renal disease.

Spherocytes

Dense-staining, smaller red blood cells that lack central pallor; produced when splenic or hepatic macrophages bite away antibody-coated membrane, representing a hallmark of canine immune-mediated hemolytic anemia (IMHA).