L17: Secondary Disorders of Haemostasis Flashcards
4x major mechanisms responsible for defective secondary haemostasis
- Inherited deficiency of one+ coagulation factors
- Vit K antagonism or deficiency (most common)
- Severe acute/ chronic hepatic parenchymal Dz
- Excessive fibrinolysis
Which are the K dependant clotting factors ?
2, 7, 9, 10
What are some clinical signs of Vit K antagonism (e.g. rodenticide) or haemophilia?
haemotoma bleeding into body cav epistaxis MM petechiae bleeding into joints
Which breeds have inherent Vit K disorders that predispose bleeding
Haemophilia –> Males (e.g. German shepherds) because X linked recessive
Inherited mutation of gene encoding carboxylase important for synthesising Vit K dependant factors –> Devon rex cats
What role does Vit K play in hepatic synthesis of coagulation factors?
required as co-factor by enzyme gamma-glutamyl carboxylase which carboxylates residues of Vit-K coagulation factors to render them functionl
how can large animals be exposed to coumarin type anticoagulants
Mouldy sweet clover or sweet vernal grass
Why is warfarin less hazardous than modern rodenticides
has shorter half life and needs platelets to be activated or something
in what circumstances might a dog develop Vit K deficiency???
prolonged anorexia
oral antibiotics that eliminates GIT bacteria that can synth it
Commercial diets generally contain excess vit K and GIT floral can synthesise and liver stores several days supply so normally not a wozz!
How much hepatic mass needs to be loss before animal is predisposed to haemorrhage???
> 70%
In which condition is excessive fibrinolysis a contributor to defective 2ary haemostasis?
Rare except in context of DIC
Which conditions predispose animals to 2ary haemostasis disorders ?
Snake envenomation
Administration of plasminogen activators
Excessive endothelial release of t-PA e.g. shock, heat stroke, severe tissue trauma
