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What causes giant platelets?
due to the increased demand for platelets and a corresponding bone marrow response.
Where are giant platelets commonly seen?
feline peripheral blood irrespective of disease state
Name the thrombocyte series.
What is this?
- thrombocyte precursor foundin bone marrow, part of thrombocyte series, massive cell which can be seen without oil, multinuclear mass, large amount of cytoplasm, thrombocytes are formed when pieces of cytoplasm breaks off
What is this?
When are clinical signs seen with thrombocytopenia?
when platelet counts fall below 50,000/ul
How many platelets are typically on a field?
8 - 10
If thrombocytopenia is suspected from the appearance of a blood smear, what should we always check?
the feathered edge for platelet clumping
Finding platelet clumps on a blood smear suggets that platelet numbers are _____.
What animal commonly has platelet clumping?
How can we reduce platelet clumping in a cat?
- reduce stress during blood sampling
- use vacutainer
- discard first several drops of the sample
- invert sample tube several times immediately after collection
- pre-analytical vortex mixing helps to disaggregate platelets
- avoid "probing" for a vein...we want a clean stick
What are dot plots and histograms?
visual representation of cell population found in a sample
What can platelet clumping impact in dogs?
eosinophil and neutrophil counts
What can platelet clumping affect in cats?
basophil and eosinophil counts
- commonly seen in feline peripheral blood irrespective of disease state
- the large size of feline platelets which overlap the small size of the normal feline erythrocyte can cause inaccuraties in automated platelet counts
What are normal results for dogs and cats in buccal mucosal bleeding time?
Should we blot the incision site when we are doing a buccal mucosal bleeding time?
no, allow the blood to flow towards the filter paper
Which types of anaplasma do the 4DX tests test for?
- Anaplasma platys
- Anaplasma phagocytophilium
Do we differentiate between the two anaplasmas on a 4DX test?
Which anaplasma causes canine anaplasmosis?
anaplasmosis is a disease caused by Anaplasma phagocytophilium
How is Anaplasma phagocytophilium transmitted by?
by the deer tick and black-legged tick
How is Anaplasma platys transmitted?
by the brown dog tick
How do we collect a sample for the Idexx Coag Dx Analyzer?
- clip hair
- wipe with alcohol
- allow alcohol to completely dry as it will affect results
What kind of needle and syringe do we use to collect blood for the Idexx Coag Dx Analyzer?
use nonheparinized 18 to 23 gauge needle
What tube is blood collected in for the Idexx Coag Dx Analyzer?
- sodium citrate tube
- allow to fill to stated draw volume
- mix immediately by inverting four times
- collect sample at least 5 minutes before running to allow for equilibration of citrate with the sample and use within 2 hours of collection
- store sample at room temperature only
What tube do we collect blood in for the SCA 2000?
blue top tube - sodium citrate
What test cartridges do we use for for SCA 2000?
use non-citrated test cartridges
What are some common errors with SCA 2000?
- timing - 5 minutes once cartridge is inserted
- key pad errors - display will alternate "add sample" and "press start", may accidentally press start before loading sample (only 12 seconds to load sample, if this happens)
- filling (trapping air bubble)
How much do cartridges for the SCA 2000 cost?
What do we use for quality control for the SCA 2000?
SCA Verification Cartridges
What types of quality control are we testing for for the SCA 2000?
quality control on this machine is tested on 2 levels of performance - normal and abnormal (high) plus temperature verification
How often should quality control be run for the SCA 2000?
- once per shift (if used frequently throughout the day)
- prior to each test (if used infrequently)
Can the SCA 2000 be calibrated in house?
no, must be sent to the supplier for this service
Are quality control and calibration the same thing?
How many thrombocytes per oil field is considered normal?
8 - 10
How do we calculate a platelet estimate?
- Count 10 fields
- Average the numbers from the 10 fields
- Multiply the average by 15,000 and 20,000 - this give you your range of platelets
At what platelet level do clinical signs start showing up?
< 50,000 thrombocytes/ul
What type of test is the SCA 2000?
citrated PT test
What does a citrated test mean?
the blood was collected into a sodium citrate tube
What does the SCA 2000 evaluate?
extrinsic and common pathways
What does the VSPro test?
PT and aPTT
How do we do a ACT (activated clotting time) test?
- prewarm one ACT tube for 3 minutes at 37 degrees celsius in the heating block
- its best to use the jugular vein for collection
- draw the blood sample being certain to draw tubes for other uses first, or discard the first tube from your drwa
- as soon as the first drop of blood enters the ACT tube - start timing
- when blood ceases to flow into the tube remove and initiate mixing (mix at least 5 times)
- one minute after blood first enters tube, and then every 5 seconds after check for first signs of clot formation by inverting the tube
- the end point of is the first unmistakable, but not solid clot and should be timed to the nearest 5 seconds
Why can't we use the first part of the blood sample when doing the ACT test?
tissue fluid thromboplastins may enter the needle and cause erroneous results
Which species is platelet clumping common in?
What does platelet clumping look like on a dot plot?
large platelet clumps appear as a curved path of dots extending from the orange area of unlysed cells paralleling the normal leukocyte cloud
How can we prevent platelet clumping?
- decrease stress when collecting blood
- discard the 1st few drops or draw red top first if using vaccutainer
- use a vaccutainer
- mix well
- use vortex
- clean stick - dont redirect alot
Cat RBCs are smaller than dogs, how can this cause a problem when running a CBC on a machine?
RBC and platelet histograms can overlap slightly
How can we tell when there is platelet clumping on the HMII?
the graph will not have any specific peaks and valleys
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