Primary haemostasis

Question 1

List the 3 steps of haemostasis

Answer 1

Primary= platelet plug
Secondary= fibrin plug that requires the coagulation cascade
Tertiary= Clot lysis

Question 2

List the clinical signs of dysfunction of primary coagulation

Answer 2

Petechiae/ ecchymoses common
bleeding from mucous membranes
often more than one site of bleeding
Haematomas rare

Question 3

List the clinical signs of dysfunction of secondary coagulation

Answer 3

Petechiae/ ecchymoses rare
Deep or cavity bleeds
can bleed from mucous membranes
sometimes single sites of bleeding
Haematomas common

Question 4

What is needed to make a platelet clot

Answer 4

cells
protein (vWF and others)
Facilitators
Physiological inhibitors

Question 5

What cells are the source of von Willebrand factors

Answer 5

Endothelial cells

Question 6

What is diascopy and what does it test

Answer 6

Does the lesion blanch under a glass slide
Yes= vascular vasodilation
No= Petechiae

Question 7

List 3 reasons why primary haemostasis be dysfunctional

Answer 7

Thrombocytopaenia
Thrombocytopathia
vWBF deficiency

Question 8

What is Thrombocytopathia

Answer 8

platelet dysfunction

Question 9

Describe how primary haemostatic disorders are investigated

Answer 9

Signalment
Platelet count and morphology
Buccal mucosal bleeding time
vWF assay
Platelet function assays

Question 10

List 3 causes of thrombocytopaenia

Answer 10

defective platelet production
Accelerated platelet removal (IMTP)
Platelet sequestration or loss (haemorrhage)

Question 11

What is the most common acquired cause of primary haemostatic defects in dog

Answer 11

IMTP- immune-mediated thrombocytopaenia

Question 12

What is Evans syndrome

Answer 12

IMHA + IMTP

Question 13

Describe how is IMTP treated

Answer 13

treat any underlying disease
Immunosuppression

Question 14

What are the negative prognostic indicators in IMTP

Answer 14

melaena
high BUN (blood urea nitrogen)

Question 15

List 3 causes of thrombocytopathia

Answer 15

Inherited
drug induced defects (NSAIDs)
platelet dysplasia

Question 16

DEcsribe how you diagnose a thrombocytopathia

Answer 16

normal platelet count but prolonged BMBT
normal levels of vWF
platelet function tests
to a degree often a diagnosis of exclusion

Question 17

Describe how thrombocytopathia is treated

Answer 17

no specific therapy
platelet transfusion not possible
withdraw any drug use (NSAID)
treat symptomatically- blood transfusion if marked anaemia

Question 18

What is the most common inherited bleeding disorder in dogs

Answer 18

vWD- Von Willebrans disease

Question 19

List te differences between the 3 types of vWD

Answer 19

1= abnormally low concentrations of structurally normal vWF
2= structurally abnormal vWF
3= Essentially no plasma vWF, diagnosed by ELISA

Question 20

What breed of dog is most prone to vWD

Answer 20

Dobermans

Question 21

What are the clinical signs of vWD

Answer 21

mucosal haemorrhage
cutaenous bleeding
prolonged bleeding from wound

Question 22

Describe the diagnostic testing used for vWD

Answer 22

platelet count will be normal
BMBT screening test
Diagnosis is confirmed by demonstration of low vWF antigen concentrations
Genetic testing can be performed

Question 23

How is vWD treated in severe cases

Answer 23

plasma - in severe cases
stabilisation
cessation of active haemorrhage
red cells if O2 carrying capacity compromised

Question 24

Describe how type 1 vWD is treated

Answer 24

Desmopressin - acts by causing release of vWF from endothelial cells

Question 25

below what platelet concentration does spontaneous bleeding occur

Answer 25

50 x 10^9