Exam 3 - Disorders of Primary Hemostasis

Question 1

what does the endothelium of the vessels synthesize?

Answer 1

collagen, fibronectin, & VWF

Question 2

what is the platelet phase of primary hemostasis?

Answer 2

platelet adhesion

1. vessel damage exposes subendothelium & platelets adhere
2. VWF helps bind the platelets to the subendothelium

platelet aggregation

3. platelet conformational change - release of substances that stimulate aggregation
4. primary plug forms serving as the surface for secondary hemostasis

Question 3

what clinical signs are associated with disorders of primary hemostasis?

Answer 3

petechiae/ecchymoses, bleeding from mucosal surfaces, melena/hematochezia/hematemesis, hematuria, & pulmonary bleeds

Question 4

what is the purpose of using a BMBT in disorders of primary hemostasis?

Answer 4

test for primary hemostatic disorder other than thrombocytopenia

Question 5

T/F: vasculitis is a common cause of primary hemostatic disease

Answer 5

false - uncommon

can cause petechiae/ecchymoses

Question 6

if vasculitis is to be definitively diagnosed for a primary hemostatic disease, what must happen?

Answer 6

biopsy is the only way to definitively diagnose

Question 7

what is von willebrand’s disease?

Answer 7

deficiency of vWF

Question 8

why does von willebrand’s disease resemble a platelet disorder?

Answer 8

VWF is a part of normal primary hemostasis

Question 9

what is the most common inherited bleeding disorder in the dog?

Answer 9

von willebrand’s disease

Question 10

when should you test for von willebrand’s disease?

Answer 10

patients that are clinically bleeding, making decisions about breeding, & prior to surgery

Question 11

how is type I VW disease characterized? what breeds are affected?

Answer 11

low concentration & normal structure of vWF - variable severity of disease

dobermans

Question 12

how is type II VW disease characterized? what breeds are affected?

Answer 12

low concentration & abnormal structure of vWF - severe

GSP & GWP

Question 13

how is type III VW disease characterized? what breeds are affected?

Answer 13

vWF markedly reduced or absent

familial - shetlands, scotties
sporadic - blue heelers, labs

Question 14

if doing a surgery on a VWD patient, what should you do in prep & have on hand?

Answer 14

prep - give VWF, cryoprecipitate & plasma

give donor desmopressin to the blood donor prior to collection

have blood products on hand in case a transfusion is required

Question 15

what are the 2 general diseases that are included in decreased platelet function?

Answer 15

VWD & thrombocytopathia

Question 16

what are some causes of acquired thrombocytopathies?

Answer 16

drugs - nsaids, clopidogrel, & high dose colloids

neoplasia

infectious agents - ehrlichia canis & platys

hepatic disease

uremia

DIC

Question 17

what are 4 general mechanisms of decreased platelet numbers?

Answer 17

1. destruction
2. sequestration
3. decreased production
4. utilization or loss

Question 18

what is the common signalment of a patient with immune mediated thrombocytopenia?

Answer 18

common in dogs, some breed predispositions, young-middle aged

Question 19

what are some primary causes of ITP?

Answer 19

idiopathic

evan’s syndrome - ITP & IMHA

systemic lupus erythematous

Question 20

what are some secondary causes of ITP?

Answer 20

infectious - ehrlichia, babesia, leishmania, leptospira, HW, FeLV/FIV

neoplasia - lymphoma, hemangiosarcoma, carcinoma

drugs - sulfas, cephalosporin, phenobarbital

Question 21

how is ITP diagnosed?

Answer 21

diagnosis of exclusion

medication/vaccine history, infectious disease testing, thoracic rads, abdominal ultrasound, FNA of enlarged peripheral lymph nodes, & bone marrow evaluation only when there is no response to therapy

Question 22

T/F: thrombocytopenia is a contraindication to bone marrow collection

Answer 22

false - not a contraindication

Question 23

how is ITP treated?

Answer 23

avoid or d/c nsaids, cage rest, avoid trauma, monitor for rapid blood loss usually through the gi tract, & transfuse with packed red blood cells or whole blood

Question 24

how does vincristine help in treating ITP?

Answer 24

• increases circulating platelet count
• accelerates fragmentation of megakaryocytes
• stimulates thrombopoiesis
• impairs platelet phagocytosis by macrophage

Question 25

what are the risks of using vincristine for treating ITP?

Answer 25

severe tissue damage if extravasated

Question 26

how do glucocorticoids help in treating ITP?

Answer 26

mainstay of therapy - immunosuppression

may also give doxycycline while tests are pending

Question 27

what is the dosage used for glucocorticoids when treating ITP? when is a response expected?

Answer 27

pred 2mg/kg/day

2-11 days - mean of 4 days

Question 28

why is a 2nd line immunosuppressive drug added when treating ITP with glucocorticoids?

Answer 28

allows for more rapid tapering of prednisone

Question 29

how does monitoring of ITP affect treatment?

Answer 29

monitor every 2-3 weeks

if platelet count is normal - taper pred by 25%

continue on pred at 0.5mg/kg every 48 hours for 2-3 weeks & discontinue

monitor for relapse!!

Question 30

what is the prognosis for most cases of ITP? what are some negative prognostic factors?

Answer 30

overall good - 89% survived to discharge

bleeding into CNS/lungs - typically fatal

60% survival rate in dogs with ITP & melena or elevated BUN

Question 31

what is the percentage of relapse of ITP?

Answer 31

31% at an average of 79%

Question 32

what are some differentials that should be considered for pancytopenia?

Answer 32

drugs - chloramphenicol, sulfas, chemo drugs, anti-fungals, phenobarbital

toxins - estrogen or radiation

infection - chronic ehrlichia, parvo, histoplasmosis

immune-mediated

dysmyelopoiesis (hematopoietic neoplasia)/myelophthisis (crowding out)

myelofibrosis - idiopathic or secondary

myelodysplasia

Question 33

what clinical signs are common in patients with a primary hemostatic disorder?

Answer 33

petechiae are common, hematomas are rare, bleeding at mucosal membranes, & bleeding after venipuncture

Question 34

what clinical signs are common in patients with a secondary hemostatic disorder?

Answer 34

petechiae are rare, hematomas are common, bleeding into muscles, joints, body cavities, & delayed bleeding after venipuncture