Aortic Thrombosis in dogs. Williams et al. 2017. JVECC Flashcards
Is aortic thromboembolism or arotic thrombosis more common in dogs?
Aortic thrombosis
Was is the most common underlying etiology of aortic thrombosis in dogs?
Kidney disease, i.e., protein-losing nephropathy
Which dogs have a better prognosis, dogs with acute versus chronic onset aortic thrombosis?
chronic onset aortic thrombosis
Under what shear conditions do “white” clots forms?
high shear condition (>10,000/s)
aortic thrombosis
What cells are aortic thrombi mostly made of?
platelets
What predominates the platelet adhesion in aortic thrombosis?
von Willebrands factor
What shear conditions are “red” clots formed under?
low shear condition (<1,000)
form in venous circulation
What cells are venous thrombi mostly made of?
larger amount of red blood cells, WBCs and fibrin
small number of platelets
what predominates the platelet adhesion in venous thrombosis?
fibrinogen
What is the main mechanism by which PLN leads to hypercoagulable state?
antithrombin loss
others:
* increased platelet reactivity
* increaed activity of FV FVII, FVIII FX
* increased vWF and fibrinogen cc
* reduced plasminogen cc
What is the suspected main contributor of arterial thrombosis in dogs with hypothyroidism?
systemic atherosclerosis
At what platelet count have dogs with ITP shown to turn from hypocoagulable to hypercoagulable?
TEG tracing showed hypocoagulable state until platelet counts exceeded 40k -> above this hypercoagulable
What is the rule of P’s?
Clinical signs of arterial thrombosis or thromboembolism:
* Pain
* Paleness
* Paresthesia
* Pulselessness
* Paresis/Paralysis
* Prostration
Of the rule of P’s, what is the most common CS in dogs with arterial thrombosis?
paresis/paralysis
Why is recombinant tissue plasminogen activator safer than streptokinase or urokinase?
- rTPA has a high affinity to fibrin-bound plasminogen compared to free plasminogen
- activates the plasminogen on thrombus but not circulating plasminogen -> avoids systemic thrombolytic state -> safer
How may aspirin prevent thrombosis?
- inhibits cyclooxygenase -> reduced thromboxane A2 production
- thromboxan A2 = potent platelet agonist
limited evidence of its efficacy
How does Clopidogrel prevent thrombosis?
platelet P2Y12 ADP receptor antagonist -> modifies platelet receptor -> prevents platelet activation and aggregation stimulated by ADP
2-4 mg/kg/day
How do you monitor efficacy of unfractionated heparin?
aPTT -> target 1.5-2.5 times normal aPTT
Why could heparin carry lower efficacy in dogs with PLN?
heparin works via AT enhancement
PLN -> if low AT -> less response to heparin
Which LMWH has a higher effect on FXa inhibition, deltaparin or enoxaparin?
Enoxaparin
What is the MOA of vitamin K antagonists?
vitamin K epoxide reductase inhibition
What is IRN?
internation normalized ratio
used to monitor response to thromboplastin
What is the mechanism of Rivaroxaban?
factor Xa inhibition
