Review of Diseases of Hemostasis Flashcards
describe quantitative and qualitative tests of primary hemostasis
quantitative:
-platelet slide estimates (smear)
-thrombogram: automated platelet count
qualitative:
-BMBT
-vWF antigen assay
describe an abnormal morphology of platelets
giant/shift platelets
-larger than RBCs, suggest accelerated thrombopoiesis (platelet regeneration)
-may also be seen with macrothrombocytopenia (CKCS)
-mean platelet volume (MPV) is generally increased
4 main causes of thrombocytopenia?
- sequestration in the spleen:
-trapping platelets within the spleen, causes mild transient decreased in platelet count
-due to splenomegaly (anesthetics), splenic congestion (GDV), splenic neoplasia (lymphoma, hemangiosarcoma) - decreased production by bone marrow
-bone marrow disease: often associated with other cytopenias
–aplastic anemia (marrow panhypoplasia), toxins (bracken fern, mycotoxin), drugs (estrogen, chemo, cephalosporins), necrosis, inflam
-infectious diseases: ehrlichia and other rickettsial, viral
-macrothrombocytopenia - increased utilization:
-DIC, vasculitis, endocarditis, SEVERE and ACUTE hemorrhage - increased destruction: immune mediated
-marked thrombocytopenia (<30-40,000 platelets/uL) with normal coagulation testing (PT, PTT)
-primary ITP: autoantibodies target platelets and megakaryocytes (cocker spaniels, poodles, old english shepherds)
-secondary ITP: antibody production triggered by an inciting cause (neoplasia, infectious disease, drugs, vaccines
-must exclude causes of secondary ITP before you can diagnose primary ITP
causes of thrombocytosis
- primary thrombocytosis:
-rare
-persistent, extreme thrombocytosis (>1 million plts/uL)
-neoplastic cause
-patients may have an increased risk of thrombosis or hemorrhage, depending on platelet function - reactive/secondary: most common
a. increased production:
–due to inflammation: inflam cytokines
–recovery from recent thrombocytopenia
secondary to blood loss or trauma
-chemotherapeutic drugs: vinca alkaloids
–iron deficiency
b. redistribution/physiologic: epinephrine-mediated response or exercise leads to splenic contraction and transient thrombocytosis
c. decreased removal: recent splenectomy causes transient thrombocytosis seen for days to weeks post op
d. excess cortisol: endogenous (cortisol) or exogenous (glucocorticoid admin)
describe abnormal platelet function
- platelet count is normal or elevated
- can be inherited or acquired
- associated with:
-adherence or aggregation
-surface membrane receptors
-ability to synthesize and release products
describe von willebrand disease
- most common hemostatic disorder in dogs
-dobermans, scotties, shelties - deficiency or abnormality of vEF
-quantitative (type 1 or 3) or qualitative (type 2) - acquired vWD is uncommon in vet med
- clinical signs:
-prolonged bleeding from wounds
-mucosal hemorrhage: epistaxis, hematuria, GI bleeding
-hemorrhage often not seen until vWF <35% - diagnosis:
-definitive requires assessment of vWF concentration and/or function
-vWF antigen concentration assay = gold standard: false increase with storage time, room temp, or using whole blood, false decrease with clotting or in vitro hemolysis
-other dx tests: electrophoresis, functional assays, genetic assays to determine carrier status
describe hyporesponsive platelets
- a cause of acquired platelet dysfunction
- due to:
-drugs: NSAIDs (COX inhibitors), calcium channel blockers
-liver or renal failure (uremia)
-marked elevation in globulins
-infectious diseases (FeLV, ehrlichia)
-DIC: excess fibrin degradation products (FDPs) interfere with platelet aggregation
review primary and secondary hemostasis from foundations ppt
sorry
describe disorders of the extrinsic pathway of secondary hemostasis
- assessed via PeT
- factor VII deficiency or inhibition
-inherited: beagles, mild disease associated with bruising
-acquired: associated with EARLY vitamin K deficiency or inhibition, factor VII has the shortest half life so first to go, only PT prolonged
describe disorders of the intrinsic pathway
assessed via PTT or ACT
- hereditary factor XII deficiency/Hageman’s disease: prolonged ACT or PTT with NO clinical bleeding
-more common in cats - hereditary factor XI deficiency/Hemophilia C: mildly prolonged bleeding after surgery
-in dogs and Holstein cattle - hereditary factor X deficiency/Hemophilia B
-X-linked so more common in males; affected males have clin signs and spontaneous internal hemorrhage can occur
-affected females are usually carriers
-seen in dogs and cats - hereditary factor VIII deficiency/Hemophilia A:
-most common inherited coag disorder
-X linked so more common in males; affected have variable clin signs and spontaneous internal hemorrhage can occur
-affected females usually carriers
-seen in dogs, cats, sheep, cattle, horses
describe vitamin K antagonism or deficiency
- affects factors II, VII, IX, and X
-often affects multiple pathways; PT and PTT prolonged, PT prolonged first due to factor VII - antagonism:
-rodenticides: may also see elevations in Ca2+
-moldy sweet clover: coumarins converted to dicumarins during spoiling leading to a bleeding disorder with chronic ingestion; seen in cattle, sheep, pigs, horses - deficiency: liver or GI disease
describe common pathway disorders
- prolonged PT and PTT
- hereditary is rare
-factor X deficiency: dogs and cats
-fibrinogen deficiency: goats, dogs - acquired: usually associated with multi-pathway disorders
describe multiple pathway disorders
- vitamin K antagonism or deficiency
-factors 2, 7, 9, 10 - liver failure: decreased production of coag factors
- DIC: can cause due to increased consumption
- multi-factor deficiency (very rare)
