Primary myelodysplastic syndromes of dogs: A report of 12 cases

Clinical bone marrow specimens submitted to the University of Minnesota's V eterinary Teaching Hospital Cytology Service over a 3-year period were eval uated for the presence of myelodysplastic features. Of 220 bone marrow spec imens examined, 30 contained dysplastic features. Twenty-seven of these dog s were evaluated further. Twelve were categorized as primary myelodysplasti c syndromes, and 15 were categorized as secondary myelodysplastic syndromes . Of the primary myelodysplastic syndromes, 4 were subcategorized as refrac tory anemia and 8 were categorized as myelodysplasia. Primary refractory an emia was characterized by nonregenerative anemia without leukopenia or thro mbocytopenia and with prolonged survival. primary myelodysplasia was charac terized by pancytopenia, greater than 5% myeloblasts in bone marrow, dyspla stic features in all bone marrow cell lines, and short survival time. Resul ts of this study indicate that differentiating primary refractory anemia fr om primary myelodysplasia has both therapeutic and prognostic significance. Dogs with primary refractory anemia tend to have prolonged survival and re spond to erythropoietin treatment, whereas dogs with primary myelodysplasia have short survival and do not respond to standard treatments.