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28 Cards in this Set
- Front
- Back
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Species whose platelets are typically larger than erythrocytes in the healthy state
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-Cat
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Platelet Production
-occurs where |
-mostly marrow
-some other sites (spleen, lungs) |
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Megakaryopoiesis
-definition |
-proliferation and maturation of megakaryocytes mostly in bone marrow
-occurs in response to Tpo |
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Thrombopoiesis
-definition |
-formation of platelets from megakaryocytes and their delivery to the circulation
-response to Tpo |
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Platelet life span
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7-10 days
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Platelet
-general function |
-repair vessels
-consumption |
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Typical platelet concentration
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-1 platelet/10 - 30 RBCs
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Methods to count platelets
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-impedence method
-optical cell cytometer |
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Problems with using the impedence method to cound platelets
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-can't differentiate small erythrocytes from platelet during iron deficiency
-can't differentiate large platelets from erythrocytes in cats |
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Important findings in a thrombogram
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-platelet clumps along the feathered edge
-large platelets (shift, giant, stress) |
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In vitro activation of platelets resulting in clumps is most common in which species
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-feline
-bovine |
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Reasons for in vitro platelet activation
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-slow/poor venipuncture technique
-delayed/inadequate mixing of blood and anticoagulant -hyperactive platelets |
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Giant platelet
-guideline for classification |
-platelet diameter > erythrocyte diameter
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Giant platelets
-common in |
-healthy cats
-cavalier king charles spaniels |
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Giant platelets
-effect on counting |
-can cause pseudothrombocytopenia with impedence cell coutners
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Inc. [Giant Platelets]
-indicative of |
-increased thrombopoiesis
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Thrombocytopenia
-hallmark signs |
-petechiae
-ecchymoses |
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Thrombocytopenia
-clinical signs |
-petechiae & eccchymoses
-epistaxis, hematochezia, melena, hematuria, hyphemia -prolonged bleeding |
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Thrombocytopenia
-major reasons |
-Pseudothrombocytopenia (platelet clumps, giant platelets)
-Dec. Production (marrow disease from drugs/infections, damage of megakaryocytes) -Inc. destruction (antibody mediated, idiopathic) -Inc. activation or consumption (vasculitis, DIC. Endotoxins) -Sequestration (endotoxins) |
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What can cause multifactorial thrombocytopenia?
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-neoplasia
-infection |
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Immune-Mediated Thrombocytopenia
-pathogenesis |
-form anti-platelet antibodies (drugs, infectious agents, idiopathic)
-antibodies bind to platelets -macrophages engulf platelets |
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Consumptive thrombocytopenia
-pathogenesis |
-there is either damaged endothelium causing collagen exposure or activated coagulation cascade causing thrombin formation
-platelets become activated -aggregate and get recruited -platlets removed from blood |
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Infectious Canine Cyclic Thrombocytopenia
-due to |
-Anaplasma platys
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How is Infectious Canine Cyclic Thrombocytopenia cyclic
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-peak parasitemia is followed by thrombocytopenia
-nadir parasitemia is followed by a rising platelet conc. |
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Infectious Canine Cyclic Thrombocytopenia
-pathogenesis |
-immune mediated destruction
-sequestration |
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Thrombocytosis
-major reasons |
-Inc. production (inflammation, Fe deficiency)
-Redistribution (exercise, excitement) |
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Hemorrhage causing thrombocytopenia
-depends on |
-degree of challenge to stop bleeding
-size of platelets -function of individual platelets -presence of vWF |
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Does blood loss cause thrombocytopenia?
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-usually not
-usually doesn't cause neutropenia either |
