Diagnosing Ineffective Hematopoiesis: PIMA, IMN, and Beyond

Presentation Description / Summary: Ineffective hematopoiesis occurs when production of hematopoietic cells is increased (hyperplasia) but the marrow is unsuccessful at releasing these new cells into blood resulting in persistent cytopenias. The most common form of ineffective hematopoiesis in small animals is ineffective erythropoiesis, most often caused by precursor-targeted immune-mediated anemia (PIMA). Another form is ineffective myelopoiesis, often caused by immune-mediated neutropenia (IMN). Other differential diagnoses for these conditions include phenobarbital toxicity, histiocytic disorders, genetic conditions, nutritional deficiencies, and osmotic fragility syndrome (cats). Pre-neoplastic or neoplastic conditions such as myelodysplastic syndrome (MDS) and erythroleukemia can mimic causes of non-neoplastic ineffective erythropoiesis, especially in cats, and will be included in the discussion. The role of FeLV infection in these feline cases will also be addressed.

Learner Outcomes: Define ineffective hematopoiesis, list differential diagnoses for this finding in dogs and cats, and describe the diagnostic approach to rule in/out each of the discussed differentials.