Hematology encompasses a broad range of topics, including hematopoiesis (production of all cell types in blood) and laboratory assessment of hematopoietic cells. Veterinary hematology is incredibly interesting, because there are marked species differences in hematopoietic cells. For instance, birds, amphibians and reptiles have nucleated erythrocytes and platelets (called thrombocytes), which makes assessment of their blood far more challenging than those of mammals. Species also demonstrate marked variability in the size of their erythrocytes, ranging from cells as small as 19 FL in sheep to as large as 120 FL in elephants. There is less variability in leukocytes and platelets in mammals, but different species do have unique responses to inflammation or immune challenge. Since animals cannot speak for themselves, we use their blood as a window into their bodies. Abnormalities in the blood can provide clues as to the presence of underlying disease (e.g. inflammation) and can be diagnostic in itself, e.g. can reveal a leukemia.
In this section of eClinPath, we will cover the following:
- Hemogram basics: Laboratory assessment of hematopoiesis is accomplished by performing a complete blood count (CBC) or hemogram on anticoagulated blood (EDTA is the typical anticoagulant used for CBCs). Here, we will provide information on how CBC is performed (including blood sample collection) and the data that is gleaned from a hemogram.
- Sample collection: How to collect and store a sample for hematologic assessment. Includes storage-associated changes (artifacts) that impact result interpretation.
- Hematologic tests: Information on erythrocyte, leukocyte and platelet tests and their diagnostic relevance. Some platelet testing, e.g. platelet function testing, is covered under the hemostasis portion of the site. We have also included a hemogram quick test guide on causes for increases or decreases in our hematologic test results (e.g. hematocrit etc), a summary table of the RBC test results from our automated hematology analyzer and how they are measured, and a summary table on combined interpretation of MCV and MCHC results.
- Morphologic features: Information on visible changes in peripheral blood cells and their diagnostic relevance. This section also includes a quick guide or a table summarizing different RBC changes, what they mean and the conditions in which they occur.
- Infectious agents: Information on infectious agents that can be identified in blood smears.
- Anemia: A diagnostic approach, including assessment of regeneration, different mechanisms (hemorrhage, hemolysis, production defect) and types (e.g. immune-mediated, oxidant injury etc).
- Erythrocytosis: Mechanisms and causes of an increased RBC mass in animals
- Pancytopenia: Mechanisms of pancytopenia
- Leukogram changes: Information on changes in different leukocytes and patterns of leukocytes and their diagnostic relevance.
- Hematopoietic neoplasia: Information on the different types of neoplasia affecting hematopoietic cells in animals, including primary acute and chronic leukemia, myelodysplastic syndrome, lymphoma and plasma cell tumors (extramedullary plasmacytoma and multiple myeloma).