platelets and coag (copy)

3 part process body tries to stop hemorrhage

Vasoconstriction: vessel spasm, reduce blood flow

Platelet adhesion: platelet plug forms

Coagulation: fibrin stabilizes platelet plug, no we have a clot

Why must we always use a blood smear when evaluating platelets?

identify platelet clumps

methods of evaluating platelets

estimate

adequate- 7-10 per oil immersion

automated analyzers

3 chemicals released when platelet plug is forming

Epinephrine- causes vasoconstriction

ADP- causes platelet aggregation

Platelet factor 3- accelerates coagulation cascade

Describe clot retraction

Platelets pull on fibrin threads and tighten the clot (completely retracted by 24 hrs)

Most common cause of spontaneous bleeding

Thrombocytopenia

What does low numbers, but large in size of thrombocytes indicate

rapid production

Symptoms of thrombocytopenia

Petechiae

Ecchymosis

Mucosal bleeding

Ethologies of thrombocytopenia

Immune mediated

Severe hemorrhage

Marrow disorder

Disseminated intravascular coagulation

Macrothrombocytopenia

Macrothrombocytopenia common in…

Cavalier King Charles spaniels

Macrothrombocytopenia Platelets are large in size and often are ____ in numbers in 50% King Charles.

Low

eitiologies of thrombocytosis

Reactive due to increased thrombopoietin, erythropoietin

Vincristine

Physiologic - adrenaline

Megakaryocytic leukemia (rare)

Acquired platelet abnormalities example

Certain nsaids

Inherited platelet function abnormalities examples

Platelet aggregation disorder

Von willebrands disease - most common, necessary for platelet adhesion to vessel walls,

What test can you do for von willebrands disease

A buccal mucosal bleeding time

Define coagulation

coagulation is the formation of the fibrin clot that stabilizes the platelet plug

Coagulation factors

glycoproteins- manufactured in liver, in inactive state

vitamin K- produces factors II, VII, IX, X

a domino like series of rapid reactions leads to…

activation of coagulation factors

Activation of coag factors occurs by 2 methods….

Intrinsic pathway- collagen exposure

Extrinsic pathway- tissue thromboplastin release from damaged vessel/ surrounding cells

What does the intrinsic and extrinsic pathways activate

common pathway in which fibrinogen is converted to fibrin by thrombin (ie fibrin stabilized platelet plug)

Prothrombin time (PT) is done using _____ collected in ___________

Plasma

Trisodium citrate

PT measures which pathway

extrinsic/ common

Partia; Thromboplastin time (PTT) measures what?

intrinsic/ common

Activated clotting time (ACT) is collected in a tube containing what

diatomaceous earth

ACT measures what

intrinsic/ common pathways

Inherited coagulation disorder

Hemophilia A- factor VIII deficiency

Hemophilia B- factor IX deficiency

Acquired coagulation disorders

liver disease

vitamin K antagonists

Disseminated intravascular coagulation (DIC) (death is coming)