This is a flow chart representing the bone marrow findings (no/few hematopoietic cells, neoplasia, ineffective hematopoiesis and necrosis) and potential causes of pancytopenia (anemia that is typically non-regenerative, neutropenia, thrombocytopenia). Note that this a general outline and does not encompass variations of the theme. For example, dysplasia in hematopoietic cells can be seen in non-neoplastic conditions causing ineffective hematopoiesis, including toxins, drugs and cancer. However, persistent cytopenias with a hyperplastic marrow and substantial dysplasia would support a diagnosis of myelodysplastic syndrome or primary myelodysplasia, which is a clonal or neoplastic disorder. The latter is quite rare in all species other than in cats (usually due to FeLV infection), where it is now less commonly seen with the advent of FeLV vaccination.