Comparison of automated versus manual neutrophil counts for the detection of cellular abnormalities in dogs receiving chemotherapy: 50 cases (May to June 2008).

Objective--To determine the frequency of clinically relevant abnormalities missed by fail-ure to perform a blood smear evaluation in a specific subset of dogs receiving chemo-therapy and to compare automated and manual neutrophil counts in the same population. Design--Retrospective case series. Animals--50 dogs receiving chemotherapy with a total nucleated cell count > 4,000 nucle-ated cells/μL. Procedures--50 blood smears were evaluated for abnormalities that have strong potential to change the medical plan for a patient: presence of blast cells, band neutrophils, nucle-ated RBCs, toxic change, hemoparasites, schistocytes, and spherocytes. Automated and manual neutrophil counts were compared. Results--Blood smears from 10 (20%) patients had > 1 abnormalities. Blast cells were identified on 4 (8%) blood smears, increased nucleated RBCs were identified on 5 (10%), and very mild toxic change was identified on 2 (4%). Correlation coefficient of the neutro-phil counts was 0.96. Analysis revealed a slight bias between the automated and manual neutrophil counts (mean ± SD difference, -0.43 X 10³/μL ± 1.10 X 10³/μL). Conclusions and Clinical Relevance--In this series of patients, neutrophil count corre-lation was very good. Clinically relevant abnormalities were found on 20% of the blood smears. An automated CBC appears to be accurate for neutrophil counts, but a microscopic examination of the corresponding blood smear is still recommended; further studies are needed to determine whether the detection or frequency of these abnormalities would dif-fer dependent on chemotherapy protocol, neoplastic disease, and decision thresholds used by the oncologist in the ordering of a CBC without a blood smear evaluation. [ABSTRACT FROM AUTHOR]