Sizing of animal erythrocytes using sulfate based diluent

Sulfate based cell counting diluent and human erythrocyte size standards were evaluated for electronically sizing erythrocytes of common domestic species. Mean differences between calculated and human cell referenced electronic mean corpuscular volume values were 0, 0.4, 0.8, and 2.1 fl for blood of dogs, horses, cats, and cows, respectively. These differences were statistically significant only for the cat (p=0.029) and cow (p=0.0002). Electronic mean corpuscular volume was measured on multiple lots of human cell control material following calibration with human cells and cells of each of the four species. There were no significant differences between assigned assay values and direct measurements at each calibration (F=0.14, df=29). Sulfate based diluent, used on some automated cell counting systems, appears suitable for sizing animal erythrocytes and commercially available human cell standards are appropriate for calibration of certain systems used in veterinary hematology.