Veterinary hematology synopsis

HEMATOLOGY

Slide preparation:
Push smear technique
Quick drying to reduce artifacts
Staining

Hematology stains:
Diff quick stain (routinely used
New methylene blue for reticulocytes and Heinz bodies

Procedure for blood film evaluation:
Scan slide at 20X magnification
Predominant leukocyte (neutrophil in dogs and lymphocyte in ruminants)
Erythrocyte arrangements
Platelet clumpsAbnormal cells
Nucleated red blood cells
Reactive left shifted, neoplastic
Erythrocyte morphology (100X)
Platelet numbers and morphology (100X)
Leukocyte numbers and morphology (100X)

Erythrocyte evaluation 100X oil magnification:
Erythrocyte morphology
changes in size, shape or color
Evaluation for presence of hemoparasites
In a normal canine blood smear RBC are evenly distributedthroughout the smear and are of same size and shape and color with a central palor with no hemoglobin which is one third of the diameter of the cell.
In feline blood, rouleaux is common and not cells all have central palor which are the spherocytes
Normal equine blood also has rouleaux and also some do not have central palor
Rouleaux: coin like stacking of RBC. Excess rouleaux is due to increasedamount of protein in the blood.ex: Increased fibrinogen
Agglutination: clumping of RBC due antibodies against RBC in immune mediated diseases.
SALINE TEST is used to distinguish between agglutination and rouleaux. Take a drop of blood and 1/2ml of saline and look under microscope. if the cells are dispersed then it is rouleaux and if it is true agglutination the clumps remain.

Erythrocytedevelopment:
Rubriblast is the most immature form found only in bone marrow with a big nucleus and basophilic cytoplasm. Not seen in peripheral blood. As the cell matures the size of the cell decreases and also the nucleus size decreases until it becomes pyknotic and dies.Before it is released from bone marrow nucleus is extruded from the cell.
The cytoplasm in rubriblast is basophilic as itmatures RNA is replaced by hemoglobin and cytoplasm becomes eosinophilic or orange color.
Variation in size of RBC is ANISOKARYOSIS
Spherocytes: seen in IMHA
Projections found on RBC which are of the same size and evenly distributed is CRENATION (artifact due to depleting ATP).
Irregular projections which are unevenly distributed, varying in size and shape are ACANTHOCYTES (True pathologiccondition). It is a true pathologic change due to disease. They result from abnormal phospholipids and cholesterol content in RBC membrane seen in patients with liver disease and also seen in certain tumors like hemangiosarcoma.
Reticulocytes are immature RBC with distorted central palor, excessive red cell membrane, no disc shape.
Pig RBC tends to crenate frequently and easily.
Schistocytes are verysmall RBC which results from fragmentation of RBC associated with thromboembolic disease or DIC. Fibrin strands form in RBC which cut the RBC forming schistocytes.

Changes in color of RBC:
Immature RBC are more basophilic in color called polychromatic cells or reticulocytes seen in regenerative anemia. They are stained with new methylene blue stain. Some RBC have small blue specks on them.These are the reticulocytes. They should be more than 1% of the total no of red blood cells in order to make sure it is regenerative anemia.
Aggregate (clumps of blue staining material) and punctuate (dispersed specks of blue stain) reticulocytes in cats. We count the aggregate reticulocytes in cats.
Reticulocyte correction =

patients PCV
--------------- * % of reticulocytes
normal PCVHypochromasia: when the central pallor is more than half the diameter of the cell with decreased hemoglobin seen in animals with iron deficiency (Chronic Anemia).

Inclusions in RBC:
Heinz bodies:
Knob like protrusions on the cell surface or pale spots inside the RBC. These are denatured hemoglobin molecules caused by oxidative damage.
Cat blood is highly susceptible to Heinz body...