Quantification of thrombopoietic activity in bone marrow aspirates of dogs

The aims of the study were to investigate possible influences of different numbers of counted fields on slides, and different slides on the counting of platelet precursors, and to establish guidelines for bone marrow examination in dogs. The study was based on bone marrow slides of 131 healthy dogs. The slides were prepared by a squash technique. On each slide the number of thrombopoietic cells at different levels of maturation were counted in all fragment-containing fields. The results of a variance component model revealed no influence of different slides, in contrast to a high variance related to different fields. Between 20 and 25 low power fields (100x magnification) had to be examined to achieve an imprecision of 20%. An imprecision of 10% required the counting of 100 fields. The lowest thrombopoietic activity was seen in the bone marrow of dogs aged one to six years. The total number of platelet percursors per field was significantly higher in adult female (10.4 +/- 2.67) than in male dogs (7.84 +/- 2.04, P = 0.0008) as was the number of megakaryocytes. We recommend assessment of thrombopoiesis on the basis of 20-25 fragment-containing low power fields and that age- and sex-related differences should be considered.