Thrombocytes Flashcards
how thrombocytes are formed
stem cells in marrow, pieces of precursor cell= megakaryocyte cytoplasm, nucleus gets phagocitized
thrombocyte lifespan
ab 9 days
how thrombocytes stain
light purple-blue
function of thrombocytes
form clots (“platelet plug” or “hemostatic plug”)
what attracts thrombocytes to the site of a vessel tear
chemicals released from blood vessel wall
what is Fibrin
proteins in blood form fibrin, binds platelets together to seal blood clot
normal canine thrombocyte count
200,000-500,000/ul
possible causes of thrombocytopenia
aplastic anemia, some bacterial and viral diseases, autoimmune diseases (platelets destroyed by body), massive hemorrage
what is aplastic anemia, what may cause?
destruction of megakaryocytes/marrow destroyed by drugs, radiation, or excessive estrogen (aplasia= no growth)
where up to 30% of platelets are stored
spleen
we may not see clinical signs of thrombocytopenia until the numbers drop below
50,000/ul
clinical signs of thrombocytopenia
slow clotting time (excessive bleeding), unexplained bruising (aka contusion)- subcutaneous bleeding
2 kinds of bruising/contusions
petechia- small pinpoint bruising (small capillaries bleeding)
ecchymoses- large area of bruising
tests to diagnose clotting issues
platelet count and total protein (fibrin)
how to count platelets indirectly
estimated count- while doing differential, scan 10 fields in oil, count all/10= average
canine platelet estimated count average
7-10/ hpf (high powered field)
what is considered a low estimated platelet count in canine
> 5 suggests problem, >3 suggests thrombocytopenia (should then do a direct count)
thrombocytosis may indicate
response to a problem such as trauma, disease, hemmorage (cause the release)
how thrombocyte production is controlled
by demand- low circulating number-> bone marrow increases number of megakaryocytes-> increased number of platelets (spleen also releases)
How to do direct platelet count
Hemocytometer and thrombotic kit
