Use of CD9 and CD61 for the characterization of AML‐M7 by flow cytometry in a dog*

Acute megakaryoblastic leukaemia (AML-M7) is a rare myeloproliferative disorder in domestic animals. Recently, thanks to the greater availability of immunophenotypetechniques, precise diagnosis is more easily made. The morphological evaluation has its limitations, especially in the study of poorly differentiated cells. Few reports have described AML-M7 in dogs using flow cytometry. This clinical case points out the utility of flow cytometry in the characterizationof AML-M7 in a 3-year-old German Shepherd dog. Flow cytometry investigation has established megakaryocytic lineage involvement by showing the presence of two megakaryocyte/platelet associated antigens (CD9 andCD61). In humanmedicineCD9 maybe used as a platelet andmegakaryocytemarker. There is an evidence of cross-reactivity of human anti-CD9 monoclonalantibody with canine samples. To our knowledge, the use of CD9 has never been described before, for this purpose in the dog.