Automated analysis of bone marrow aspirates from dogs with haematological disorders

Automated analysis of bone marrow (BM) aspirates is a useful 'pre-microscopical' screen to identify hypocellular samples and those with potentially abnormal cells. In order to determine whether automated analysis could also be used to identify haemopoietic abnormalities, EDTA-anticoagulated BM aspirates from 43 dogs were analysed using the Advia 2120 instrument. Corresponding Wright-stained BM smears were evaluated microscopically to determine smear quality, cell composition and 500-cell differential counts, and correlation to automated analysis parameters was computed. Leucocyte cytograms generated by the automated analyzer were scrutinized and compared with those of 'normal' BM. Twenty-three neoplastic and 20 non-neoplastic samples were analysed, including samples from 10 cases of acute myeloid leukaemia, four cases of acute lymphocytic leukaemia, four cases of chronic lymphocytic leukaemia, one case of chronic neutrophilic leukaemia, three cases of multiple myeloma, one case of myelodysplastic syndrome, five cases of non-regenerative immune-mediated haemolytic anaemia, one case of immune-mediated neutropenia, three cases of immune-mediated thrombocytopenia, six cases of inflammatory disease, three samples with myelotoxicity and two samples analysed for staging of neoplasia. Automated white blood cell (WBC) counts correlated significantly with smear cellularity, particle cellularity and particle number. There was a significant difference in WBC counts of samples with insufficient versus sufficient particles. Significant correlations between Advia percent neutrophils and microscopical determination of marrow segmented neutrophils/neutrophilic granulocyte reserve, Advia percent lymphocytes and microscopical determination of lymphocytes/rubricytes, Advia percent large unstained cells and microscopical determination of myeloblasts/promyelocytes and between Advia percent eosinophils and manual determination of eosinophils were identified. This suggested that Advia WBC counts may be used to approximate BM sample quality and that Advia differential counts may predict marrow granulocyte reserve and lymphocyte/rubricyte stores. Distinct and consistent alterations in cytogram patterns were observed in cases of acute leukaemia, but were less obvious in chronic leukaemia. Complete automated BM analysis was performed in approximately 2 min, while staining and coverslipping of BM slides required approximately 30 min. Hence, although automated analysis should not supplant microscopical evaluation of BM, it can provide useful ancillary information in a short time and flag potentially inadequate or abnormal samples.