Hematopoietic Disorders Associated with Poorly Regenerative Anemias

Many congenital and acquired bone marrow disorders have been described in dogs. Major categories include infectious diseases, immune-mediated bone marrow destruction, toxic marrow injury, congenital and acquired myelodysplastic syndromes, acute and chronic myeloproliferative and lymphoproliferative disorders, primary polycythemia, primary and secondary myelofibrosis, malignant histiocytosis, hemophagocytic syndromes, and aplastic pancytopenia. Because choice of therapy and prognosis for these disorders vary markedly, establishing a definitive diagnosis is essential. Bone marrow aspiration and core biopsy techniques are important diagnostic tools for evaluating hematologic disorders in dogs. Sample collection and initial assessment of the adequacy of bone marrow aspiration smears can readily be done in a practice setting, but detailed evaluation of aspiration smears and core biopsy samples are best done by veterinary clinical laboratories. The greatest challenge for clinicians is interpreting bone marrow reports in terms of diagnosis, prognosis, and treatment approaches. Results of bone marrow cytology must be interpreted in light of history and physical findings, changes in peripheral blood, and concurrent disease conditions. In this review, we concisely discuss canine bone marrow disorders and focus on how results are integrated with the case history and peripheral blood alterations to reach a diagnosis. We group these disorders in general categories, including hematologic disorders associated with poorly regenerative anemias, neutropenia, multiple cytopenias, and neoplastic conditions. HEMATOPOIETIC DISORDERS ASSOCIATED WITH POORLY REGENERATIVE ANEMIAS Disorders associated with poorly regenerative anemias include the following: • Erythroid hypoplasia denotes a decrease in erythroid elements in bone marrow. • Erythroid aplasia denotes a marked decrease or absence of erythroid elements in bone marrow. • Erythroid maturation arrest refers to a condition in which normal or CE 784 Vol. 24, No. 10 October 2002 n Pathologic alterations in bone marrow must be interpreted in light of the case history, concurrent diseases, and changes in the peripheral blood. n General categories of pathologic changes include immunemediated destruction, toxic injury, myelodysplastic syndromes, leukemia, macrophage proliferative disorders, myelofibrosis, and aplastic pancytopenia. n Treatment and prognosis depend on establishing a specific