Hematology

The five major categories of leukocytes in mammals are neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The first three collectively are called granulocytes, because they contain granules in their cytoplasm, and the latter two collectively are called mononuclear cells in reference to their round nuclei. These collective terms are somewhat misleading since some granulocytes have barely perceptible granules […]

White blood cell morphologic features are less species-dependent than red blood cells, although there are some species peculiarities (e.g. neutrophils in healthy cats can have low numbers of small Döhle bodies). The same basic principles are followed for identifying leukocytes in different animal species, with the exception of exotics and small mammals (which have heterophils

Changes in leukocytes in blood are incredibly helpful in identifying underlying physiologic (e.g. stress) and systemic disease processes, such as inflammation. These changes include morphologic features of leukocytes (which are covered in a separate section under hematology) as well as changes in numbers. For some leukocytes, only increased numbers are clinically relevant, whereas decreased numbers

In this section, we will outline characteristic morphologic changes in blood cells that help us identify disease processes or pathologic mechanisms. Assessment of morphologic features of red and white blood cells and platelets is an essential part of blood smear examination. Examination for morphologic changes in cells is important because these changes can be useful markers of underlying

Neutrophils Neutrophils are produced in bone marrow, released into blood after completing their maturation in marrow, circulate for less than a day (5-15 hours), and migrate out of the vessels into tissues or into alveoli and gut lumen. Effete neutrophils (that have finished their lifespan) undergo apoptosis and are removed by macrophages, in a process

Agglutination Agglutination refers to the phenomenon where red blood cells stick together in three-dimensional clumps. Agglutination is due to the binding of antibodies to red blood cells. When single antibodies bind to more than one blood cell, agglutinates form. Agglutination is usually a pathologic finding and supportive of a diagnosis of immune-mediated hemolytic anemia (IgM

Reactive lymphocytes are seen in peripheral blood as a response to antigenic stimulation. Thus, they are more frequently in younger animals, who are antigenically naive. Any disease process can induce antigenic stimulation and result in the presence of reactive lymphocytes in circulation, thus it is a relatively non-specific finding. Reactive lymphocytes are heterogeneous – they

Platelet counts can be done manually using a hemocytometer or with an automated analyzer. Counts can also be estimated during blood smear examination. Since many laboratories use instruments that count platelets, red cells and leukocytes concurrently, a platelet count is a routinely reported result on complete or automated hemograms. At the Clinical Pathology Laboratory of

The white cell count (WBC) is the total number of leukocytes in a volume of blood, expressed as thousands/µL. As with the RBC, the WBC can be done by manual methods or by automated cell counters. The WBC by any method is a count of nuclei or total nucleated cell count. If nucleated red blood

Nucleated red blood cells (nRBCs) are counted (regardless of technique, i.e. manual or automated) as white blood cells (WBC). For this reason, the obtained or measured “WBC” count (from an analyzer or a hemocytometer) is actually a nucleated count which includes WBC and nRBC. The obtained nucleated count must be corrected for the number of