9. Platelet Evaluation Flashcards
What are unique of platelet morphology compared to other species?
Mammalian platelets do not have a nucleus, therefore, not a true cell. They are cytoplasmic fragments of megakaryocytes
Bird, reptile and amphibian platelets contain a nucleus and are true cells
What is the typically mammalian platelet morphology?
Pale blue cytoplasm containing varying amounts of pink granules
What is unique about the canine platelets?
Vary in size/shape
usually sm, round, w/ distinct pink to purple granular cluster in the center while periphery is pale blue
May have long, thread-like processes extending out in all directions
What is the morphology of feline platelets?
look similar to canine platelets
cigar-shaped and giant platelets (sim size to RBCs) more common in cats and MUST BE REPORTED - bc it could look like WBC’s
Inc tendency for platelets to clump
What is unqieu about equine platelets
Indistinct, often described as “ghostly” in appearance - very pale and may be difficult to see
Granules are difficult to see and are few in number
Platelet counts are often low in healthy animals
What are unique about bovine platelets
Granules are prominent
platelets usually sm but giant forms do occur
pseudopod-like projections may be present
individual platelets often appear superimposed on red cells and must be differentiated from parasites
platelet counts are often high in healthy animals
What should you do if you are having a hard time finding platelets?
Scan feathered-edge of the smear to check for aggregates/clumping
Clumping is common, they are larger entities and are “sticky”
when smear is made, clumps get pushed to feathered edge
Clumping is to be reported
Sometimes clumps are so numerous and/or large that platelet counts are not accurate
What are giant platelets?
Megathrombocytes
Can be bigger than RBC’s
Giant, cigar shaped and other oddly shaped platelets should be noted on report
giant platelets may affect total RBC and platelet counts generated by automated analyzers
Define thrombocytopenia?
A dec in circulating platelet mass
Define thrombocytosis?
An inc in circulating platelet mass
Define thrombopathia
alteration in platelet func
Dz
What do we evaluate when looking at platelets?
The count or esitmate
Indices and function tests
Why might we do a platelet function test?
Epistaxis, petechia, or unexplained hemorrhages - used to eval for evidence of thrombopathia
What is platelet enumeration?
most often don using automated analyzers
can be very inaccurate due to platelet clumping, similarity in size to RBCs - problem in cats
Need to use a fresh EDTA blood sample and make sure there are no clots
How do you estimate platelets?
Platelet estimate is performed by examining the blood smear in the monolayer region - should always be done as part of QC for your machines
Count a min of 5 oil immersion fields of view - normal patient will have btw 7-10 platelets/hpf
