Behavior of red cell distribution width (RDW) in a population of anemic and non-anemic dogs from an ambulatory care unit.

ABSTRACT The aim of this study was to evaluate the behavior of the red cell distribution width (RDW) in the interpretation of the Complete Blood Count (CBC) from anemic and non-anemic dogs. Currently, automated veterinary blood cell analyzers provide hematologic indices not calculated in manually performed CBC, such as Red Blood Cell Distribution Width measured by Variation Coefficients (RDW-CV) and Red Blood Cell Distribution Width measured by Standard Deviation (RDW-SD), which has led to new approaches to patients with anemia, providing a quantitative measure of anisocytosis. In this study, data from 454 blood tests were reviewed within the period of September 2009 to March 2011. Mean and standard deviation were calculated and variance analysis was performed. Anemic dogs (125/454) presented higher values for RDW indices. In non-anemic animals, these indices were in accordance with the normal values previously established. Both indices were higher in dogs with microscopic observation of anisocytosis. There was a significant difference among indices of the animals which showed normal and increased Mean Corpuscular Volume (MCV). We concluded that RDW-CV and RDW-SD indices were sensitive to small variations on erythrocyte size and heterogeneity, being more accurate than microscopic observations to detect anisocytosis and more sensitive than MCV to erythrocyte variation. Keywords : anemia, anisocytosis, automated cell analyzers, hematology