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TodAy's VeTerinAry PrAcTice | July/August 2015 | tvpjournal.com in-cLinic HeMAToLoGy Peer reviewed 44 the smear can be more diffcult (Figure 1C) 2. note the presence of: • rouleaux (Figure 2): "coin stacks" indicative of inflammation or hyperproteinemia that disperse with addition of saline. A mild degree of rouleaux formation is common in cats, and the amount present in Figure 2 would be considered normal in cats • Agglutination (Figure 3): "Grape clusters" or doublets and triplets indicative of immune-mediated interactions that do not disperse with saline 3. observe any bias in cell distribution, such as concentration of leukocytes at the feathered edge that may bias cell count estimates 4. evaluate for the presence of microflaria (Figure 4) 5. identify platelet clumps that might artifactually decrease platelet numbers (Figure 5). next, move to a higher magnifcation (50× or 100×) within the counting area, and be sure to: 1. Perform a manual differential cell count to verify the analyzer results because this data can be misleading, especially when there are morphologic abnormalities 2. Assess red cell morphology, including the presence of inclusion bodies or parasites 3. Assess white cell morphology 4. note platelet density to verify analyzer data 5. note small platelet clumps and the presence of large platelets. FIGURE 2. Feline blood flm with rouleaux (arrows) present, which appear as stacked erythrocytes (similar to a column of coins); this amount of rouleaux is normal in cats. Wright- Giemsa stain; magnifcation, 200×. FIGURE 3. Grapelike clusters of agglutinated RBCs (arrows) can be seen in canine patients with immune-mediated hemolytic anemia. Wright-Giemsa stain; magnifcation, 200×. FIGURE 4. Diroflaria immitis microflaria at the feathered edge of a canine peripheral blood smear. This patient was positive on heartworm antigen testing. Note that many RBCs have lost central pallor along the feathered edge of the sample, making their appearance very similar to that of spherocytes; the leukocytes appear distorted (arrows). The loss of central pallor is likely secondary to thinning of the blood smear at the feathered edge, and leukocyte distortion is likely secondary to dragging of cells to the feathered edge that can occur during slide preparation. Wright-Giemsa stain; magnifcation, 200×. FIGURE 5. Diffuse large platelet clumping along the feathered edge of a feline blood flm. Occasionally, platelets stain extremely faint, making them diffcult to identify. Wright-Giemsa stain; magnifcation, 200×.