Hematology 2 study guide Flashcards
4 distinct functions of platelets
1) maintain vascular integrity
2) stop bleeding by forming plugs
3) facilitate secondary hemostasis and fibrin formation
4) promote vascular healing
thrombocytes are produced in what organ?
bone marrow
what cytokine stimulates the production of thrombocytes?
thrombopoietin
average lifespan of the platelet
3-7 days
how are platelets evaluated on a blood smear
count # of platelets in a minimum of 10 fields (100x) and average them together
clumping of thrombocytes is a common finding in which species?
cats
List 3 clinical signs of a decreased platelet count.
petechiae, ecchymosis or bruising, bleeding
what are the 3 categories of increased platelet counts?
essential thrombocytosis, secondary to disease, physiological
List 3 clinical signs of a systemic bleeding disorder.
bleeding in more than one location, no hx of trauma, amount of bleeding is greater than anticipated
what are the 2 types of platelet function disorders?
acquired and inherited
list the two kinds of acquired platelet function disorders.
hypo-responsiveness, hyper-responsiveness
what is hemostasis?
the ability of the body systems to maintain the integrity of the blood and blood vessel walls, platelets, and coagulation factors
what are the 2 classifications of hemostasis?
primary hemostasis (mechanical phase), secondary hemostasis (chemical phase)
how many factors are involved in the clotting cascade?
13, technically 12 because 6 does not exist
when should a coagulation assessment be performed?
perform if bleeding disorder is suspected, or if part of presurgical screening protocol
what is the preferred anticoagulant for coagulation assessments?
sodium citrate
what are the normal clotting times for PT, aPTT, and activated clotting times?
PT: 6-20 seconds for clot to form, aPTT: ~60 seconds for normal results, activated clotting times: 120 seconds for dogs and 90 seconds for cats
what is PIVKA and what is it most useful for testing?
proteins induced vitamin K absence; useful by differentiating between rodenticide and primary hemophilia
List 3 breeds of dogs commonly affected by Von Willebrand’s Disease.
Doberman Pinscher, Scottish Terrier, Airedale Terrier
What is thrombocytopenia and what are some causes?
decrease in the # of platelets; causes can include bacterial or viral infection, parasitic agents, bone marrow depression, autoimmune disease
Describe the manual method of blood collection.
need an appropriate sized needle and syringe. collection tube of choice. ensure syringe is the size of the total amount of blood needed. always remove needle and cap of tube to transfer sample. get a flash of blood when you hit the vein
Describe the vacuum method of blood collection.
collect multiple tubes at once. composed of a needle, needle holder, and collection tubes. many tubes available for use in various sizes and chemical makeup. do not see a flash when you hit the vein.
what is the vein of choice for most venipuncture in most species?
jugular
what is an anticoagulant?
any chemical that prevents or delays coagulation
