Exam 3 - Disorders of Secondary Hemostasis Flashcards
what is TF? why is it important?
tissue factor - present on membrane of most cells & is released when trauma occurs activation factor VII - the main activator of coagulation
what is the main factor that serves as the activation factor of coagulation?
factor VII
what is responsible for the production of factor VIII?
vascular endothelial cells - still requires liver function for activation
what factors are included in the intrinsic pathway?
XII, XI, IX, VIII
what factors are included in the extrinsic pathway?
VII
what factors are included in the common pathway?
X, V, II, I
T/F: a single factor must be <30% to cause a prolongation of PT/PTT
true
what is the pathogenesis of anticoagulant rodenticide toxicity?
rodenticides inhibit the enzyme that regenerates vitamin K
vitamin K is essential for factors II, VII, IX, & X
when do animals develop clinical signs from anticoagulant rodenticide toxicity?
1-4 days
how is anticoagulant rodenticide toxicity diagnosed?
based on Pt, PTT, & history of exposure
what are some examples of anticoagulant rodenticides?
warfarin, diphacinone, brodifaccoum
what are some examples of anticoagulant rodenticides?
warfarin, diphacinone, brodifaccoum
what coagulation test is the first to be prolonged in anticoagulant rodenticide toxicity? why?
PT
factor VII has the shortest half-life, so it’s affected first
what is the treatment for recent ingestion of anticoagulant rodenticide?
induce vomiting, give activated charcoal, & treat with vitamin k1
what are the 7 disorders covered for disorders of secondary hemostasis?
- vitamin k antagonist rodenticide toxicity
- vitamin k deficiency
- liver dysfunction
- inherited coagulation factor deficiencies
- disseminated intravascular coagulation
- drugs
- snake envenomation
what does PT evaluate?
extrinsic & common pathways - factors VII, X, V, II, & I
PT may be prolonged due to deficiency/dysfunction of what 2 factors?
VII & X
other than factor deficiency/dysfunction, what other conditions can cause a prolonged PT?
liver dysfunction, disseminated intravascular coagulation, heparin administration, or hypofibrinogenemia
what does PTT evaluate?
intrinsic & common pathways - factors XII, XI, IX, VIII, X, V, II, & I
PTT may be prolonged due to deficiency/dysfunction of what factors?
factors VIII, IX, XII, XI, II, V, X
PTT may be prolonged due to deficiency/dysfunction of what factors?
factors VIII, IX, XII, XI, II, V, X
other than factor deficiency/dysfunction, what other conditions can cause a prolonged PTT?
heparin therapy, liver dysfunction, hypofibrinogenemia, dysfibrinogenemia, or DIC
what does the activated clotting time assess?
intrinsic & common pathways
what is hemophilia a?
congenital deficiency of factor VIII that is x-linked, so it’s carried by females & manifested in males
what clinical signs are commonly seen in hemophilia a?
severe, spontaneous bleeding, bleeding into joints & skeletal muscle is common, some patients die within a few weeks of life
what abnormalities are seen on diagnostic tests for patients with hemophilia a?
prolonged PTT with a normal PT
what is the treatment for hemophilia a?
give fresh plasma or cryoprecipitate which contain factor VIII to control bleeding
how is hemophilia a diagnosed?
confirmed with specific factor assay
what abnormalities are seen on diagnostic tests for patients with hemophilia b?
prolonged PTT with a normal PT
what is hemophilia b?
uncommon congenital deficiency of factor IX occurring in dogs & cats
what is hageman deficiency?
factor XII deficiency especially common in cats
what abnormalities are seen on diagnostic tests for patients with hageman deficiency?
prolonged PTT - but patients don’t bleed abnormally
factors II, VII, IX, & X are made in the liver but require what for the final step of synthesis?
vitamin K
what enzyme is inhibited in anticoagulant rodenticide toxicity?
vitamin K epoxide reductase - responsible for vitamin K regeneration
why is vitamin k not given IM or IV?
IM - not given because of hematoma formation
IV - avoid due to risk of anaphylaxis or heinz bodies formation
what can cause vitamin k deficiency?
severe cholestatic liver disease, severe small intestinal disease
how do you treat vitamin k deficiency?
supplement with subcutaneous vitamin K
what is DIC?
mixed disorder of primary & secondary hemostasis
caused by abnormal activation of the coagulation system & an imbalance between coagulation & fibrinolysis resulting in the formation of thrombi in circulation causing consumption of platelets & coagulation factors
what abnormalities are seen on diagnostic tests for patients with DIC?
thrombocytopenia, prolonged PTT and/or PT, normal to low fibrinogen, elevated d-dimers, & decreased antithrombin concentration
schistocytes on blood smear
what therapy is used for treating DIC?
aimed at treating the underlying cause, halting abnormal coagulation, maintaining organ perfusion, & preventing secondary complications
prior to doing a liver biopsy, what is critical to evaluate?
coagulation panel
what bleeding disorder is a common congenital coagulopathy of cats? what symptoms do they have?
hageman deficiency - factor XII
typically asymptomatic
