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tvpjournal.com | July/August 2015 | TodAy's VeTerinAry PrAcTice in-cLinic HeMAToLoGy Peer reviewed 43 in-clinic Hematology: The Blood Film Review Leslie Sharkey, DVM, PhD, Diplomate ACVP (Clinical Pathology), and Daniel Heinrich, DVM University of Minnesota A complete blood count (cBc) is a critical component of the minimum laboratory database for evaluating veterinary patients. The proliferation of in-clinic analyzers facilitates rapid turnaround time that can improve patient care. However, microscopic evaluation of a blood flm is required to not only verify analyzer results but identify critical diagnostic features that analyzers cannot evaluate. diagnostically essential morphologic abnormalities can be present even in patients with quantitatively normal results for all hematologic parameters. EVALUATING BLOOD FILMS Prepare blood flms immediately after an atraumatic sample is collected to avoid the potential for pre- analytical error and in vitro artifacts. Hand dipping using well-maintained diff-Quik type stains is used with success for in-house staining, with a limitation of poor staining of some mast cell granules. new methylene blue should be on hand for highlighting reticulocytes and Heinz bodies. in reference laboratories, automated stainers are often utilized for a slightly more complex process that enhances some cytologic features, such as chromatin patterns, for more advanced diagnostic evaluation. s can the smear at low magnifcation (10×), and be sure to: 1. note red and white blood cell densities in the counting area (Figure 1A), which is a few frames back from the feathered edge (Figure 1B), where cells occur in a monolayer; evaluation deeper in C A B FIGURE 1. Low magnifcation canine blood flm (200×, Wright-Giemsa stain) illustrating the counting area of the slide, which contains red blood cells (RBCs) in a monolayer with minimal overlap; leukocytes present are minimally distorted. The image is taken at 200× instead of 100× due to distortion caused by the microscope imaging program (A). Canine blood flm at the feathered edge of the slide is too distorted to easily evaluate cell morphology. White blood cells (WBCs) can become distorted and RBCs can appear as spherocytes (B). Representative feld of the body of a canine blood flm, which is too thick to evaluate individual RBC and WBC morphology; RBCs are stacked on each other, with leukocytes compressed or distorted (C).