On a Diff-Quik stained blood smear from an animal with regenerative anemia, which finding is most typical?

• A. Polychromasia
• B. Schistocytosis
• C. Reticulocytosis
• D. Eosinophilia

Answer: (A)

When the body is experiencing regenerative anemia, the bone marrow pumps out more immature red blood cells (reticulocytes) to replace those lost. These young cells still contain RNA, which stains differently and gives the cells a bluish, more colorful appearance on a Wright-type stain like Diff-Quik. That variation in color across the red cell population is called polychromasia, and it is the classic smear clue that regeneration is occurring.

Schistocytosis would indicate fragmented red cells from mechanical destruction or microangiopathic processes, not the normal regenerative response. Reticulocytosis is the underlying process, but on a Diff-Quik-stained smear, the visible cue is polychromasia rather than identifying reticulocytes specifically (reticulocytes are best seen with supravital stains). Eosinophilia involves white blood cells, not red blood cells, so it wouldn’t be a smear finding you’d associate with regenerative anemia.