Lecture 17

Question 1

4 mechanisms responsible for defective secondary hemostasis

Answer 1

inherited deficiency of one or more coag factors
vitamin K antagonism or deficiency(most common)
severe acute or chronic hepatic parenchymal disease
excessive fibrinolysis

Question 2

In which domestic animal species are inherited coag factor deficiencies most often recognized? Why are purebreds most affected?

Answer 2

dogs

it is inherited as an X-linked recessive disorder (homozygous male)

Question 3

Why can some animals have a hereditary deficiency of a particular coag factor and either never bleed excessively or suffer only minor hemorrhage?

Answer 3

redundancies and amplification loops in the coag cascase

Question 4

Which of the inherited coagulopathies predispose to severe hemorrhage?(6)

Answer 4

hemophilia C (factor 11)
hemophilia A (factor 8)
Factor 10
factor 2
factor 1
Factors 2, 7, 9, 10- due to defective gamma glutamyl carboxylase (vit K)

Question 5

Why do hemophilia A and B mainly affect male animals?

Answer 5

X linked recessive disorder- males only need one X chromosome with the gene to be affected

Question 6

Which coag factors are deficient in the inherited coagulopathy recognized in devon rex cats

Answer 6

Vit K dependent factors (2, 7, 9, 10)- mutation of gene encoding gamma glutamyl carboxylase

Question 7

What role does Vit K play in hepatic synthesis of coagulation factors?

Answer 7

Vit k is cofactor to enzyme gamme glutamyl carboxylase

factors 2, 7, 9, 10 are vit K dependent

Question 8

What is the most common cause of vit K antagonism in domestic animals

Answer 8

ingestion of anticoagulant rodenticide (warfarin)

Question 9

How can a large animal become poisoned by courmarin type anticoagulants?

Answer 9

mouldy sweet clover or sweet vernal grass
Naturally contain bishydroxycoumarin-> active dicoumarin when the plants spoil
calves especially susceptible

Question 10

Why do more potent anticoagulant rodenticides pose a greater hazard to small animals than does warfarin?

Answer 10

warfarin needs repeat ingestion

newer is more potent- 1 ingestion and longer half life(can eat dead rodents and be affected)

Question 11

In what circumstances might a dog develop deficiency of Vit K?(3) is vit k deficiency common?

Answer 11

prolonged anorexia or malnutrition
oral antibiotic use
complete extrahepatic bile duct obstruction
it is rare

Question 12

What role does the liver play in hemostasis?

Answer 12

synthesizes coagulation and anti coagulation factors

removal or loss of more that 70% of the liver

Question 13

in which condition is excessive fibrinolysis a contributor to defective secondary hemostasis in domestic animals?

Answer 13

DIC

Question 14

Excessive fibrinogenolysis is thought to be contributor to defective secondary hemostasis in (3)

Answer 14

snake bite
administration of plasminogen activators
excessive endothelial release of t-PA(shock, heat stroke, severe tissue trauma)