Differential leukocyte counts determined in chicken blood using the Cell-Dyn 3500

Background: Automated hematology instruments commonly are used for mammalian blood analysis, but there is a lack of accurate automated methods available for avian leukocyte analysis. Objective: The aim of this study was to validate differential leukocyte counts in blood from chickens using the Cell-Dyn 3500 hematology system and avian-specific software.
Methods: Blood samples were collected in lithium-heparin tubes from 2 groups (n = 84 and n = 139) of laying hens. Manual 200-cell differential counts were done on routinely-stained blood smears, and manual total granulocyte counts (heterophils and eosinophils) were done using an eosinophil stain in a counting chamber. Automated differential counts were done using VET 2.3, a research and development version of avian-specific software for the Cell-Dyn 3500. Results were analyzed using Pearson's correlation and difference plots.
Results: Automated granulocyte counts from the Cell-Dyn were in good agreement with manual granulocyte counts ( r = 0.93 and 0.80 for the 2 study groups). No correlation was found between automated and manual lymphocyte counts. Correlation coefficients for monocyte counts were 0.70 and 0.43. Conclusion: Automated leukocyte results from the Cell-Dyn using VET 2.3 software were not fully accurate. Total granulocyte counts may be of clinical usefulness, but results obtained for other parameters were unreliable.