A Comparative Study of the Ovine Haemogram: Cell-dyn 3500 versus Manual Methods

Manual hematology techniques traditionally applied in farm animal medicine are time consuming and laborintensive, especially when large numbers of samples have to be processed. As a result, several automated hematology instruments have been developed for use in these species. An automated hematology analyzer (Abbott Cell-Dyne 3500 system) was used in performing a complete blood cell count and differential counts of white blood cells in sheep blood samples. The system was compared with basic manual hematologic techniques. A linear regression was used to assess correlation between the two methods. Correlation coefficients (R2) were good for the hematocrit, the total white blood cell count, the neutrophils, the lymphocytes and the platelet count, while a poor correlation existed in monocytes, eosinophils and basophils. The automated and the manual technique were also compared in terms of sensitivity using the Sensitivity Ratio (SR). The automated analyzer was slightly more sensitive than the manual technique for all parameters tested except for monocytes, eosinophils and basophils were the difference was greater and the automated analyzer was 1.5, 2.5 and 2 times more reliable, respectively. The method bias was also calculated. It seems that the overall performance of the automated analyzer justifies its utilization in sheep blood analysis, although as for any analyzer used in any species, a stained blood film evaluation remains an indispensable technique to confirm the results being reported by the automated analyzer and provide additional information for the ovine haemogram.