Association of mean platelet volume and bone marrow megakaryocytopoiesis in thrombocytopenic dogs: 60 cases (1984-1993).

Medical records of 60 thrombocytopenic dogs in which platelet volume analysis was performed between 1984 and 1993 were reviewed. Information collected from the records included signalment, mean platelet volume, the clinical pathologist's assessment of the adequacy of the megakaryocyte population in the bone marrow, and the causes of thrombocytopenia. In all dogs, the bone marrow aspirate had been collected within 48 hours of platelet volume analysis. Sensitivity and specificity of using platelet volume analysis (mean volume < or = 12.00 microns 3 vs mean volume > 12.00 microns 3) as a test for bone marrow megakaryocyte response (adequate vs inadequate) in thrombocytopenic dogs was determined. Sensitivity was 88%, specificity was 80%, predictive value of a positive test was 96%, and predictive value of a negative test was 57%. Results suggested that megathrombocytosis in a thrombocytopenic dog was a good predictor of adequate bone marrow response (normal or hyperplastic bone marrow megakaryocyte population); however, a mean platelet volume < or = 12.00 microns 3 in thrombocytopenic dogs was not strongly predictive of inadequate bone marrow response.