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NAVLE® Question of the day

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July 5, 2024

NAVLE

Which of the following correctly describes the cells on this canine blood smear?

A - Polycytosis, macrochromasia, one Heinz body

B - Heterochromic, microcytic red blood cells, Babesia canis parasitism

C - Polychromasia, anisocytosis, spherocytosis

D - Anisochromasia, red blood cell ghosts, rubricytes

E - Macrocytic, hypochromic red blood cells, plasma cell, Anaplasma marginale

Sorry. You chose "A - Polycytosis, macrochromasia, one Heinz body" but the correct answer is "C - Polychromasia, anisocytosis, spherocytosis"

This canine blood smear shows polychromasia, anisocytosis, and spherocytosis. Polychromasia and anisocytosis are evidence of a regenerative anemia, so perform a reticulocyte count to confirm a regenerative response.

Polychromasia is variation in red blood cell (RBC) color; anisocytosis is variation in RBC size.

Spherocytosis typically occurs due to immune-mediated damage to the RBC membrane resulting in a rounded (i.e., spherical) appearance to the RBC. This is seen most commonly in dogs with immune-mediated hemolytic anemia (IMHA), but may occur secondary to blood transfusion, so always interpret with caution.

Reticulocytes are immature RBCs, released early from the bone marrow; use new methylene blue staining to identify these cells. Look for reticulocytosis with regenerative anemia in most species except horses. The reticulocyte count is a measure of the bone marrow response to anemia.

For more info and images, see the Cornell Clin Path website: RBC Morphology and Hematology Atlas.

Image courtesy of Seth Chapman, DVM, MS, DACVP.