Rodenticide Coagulopathy Flashcards
What happens during primary hemostasis? What are the 2 key players?
Formation of platelet plug
- injury to blood vessel wall initially causes vasoconstriction to decrease blood flow thru injured vessel while also attracting platelets
- von Willebrand factor makes the platelets sticky enough to adhere to the vessel wall
What happens during secondary hemostasis? What are the 2 main types of players?
activation of coagulation cascade and fibrin clot formation
- clotting factors and cofactors (vit. K and calcium)
- recognition of platelet plug –> platelets provide scaffolding for clotting factors to bind and begin depositing fibrin –> fibrin forms a seal over and in the vessel wall defect
Define coagulopathy
a disease or condition affecting the blood’s ability to coagulate or form a clot to stop hemorrhage from ocurring
What is the purpose of anticoagulant rodenticide? How are pets exposed to it?
- purpose = to kill pests by making them unable to control hemorrhage, so they die of blood loss
- pets get exposed either by direct consumption or by eating a pest that has ingested the product
What does anticoagulant rodenticide do to the coagulation pathway?
- interferes with vit. K production by the liver
- inability to activate vitamin K dependent clotting factors –> coagulation cascade can’t be completed –> fibrin clot is not formed –> bleeding continues
First vs second generation rodenticide
First Gen
- shorter duration
- multiple doses for toxic effect
- clinical effect lasts appx 1 week
Second Gen
- longer duration
- 1 dose for toxic effect
- clinical effects lasting appx. 1 month
When do clinical signs appear?
12-24hrs post ingestion because the body has some vitamin K that’s already been made but not yet used
Clinical signs of anticoagulant rodenticide
- Anemia (lethargy, weakness, depression) due to hemorrhage
- Other clinical signs depend on hemorrhage location
CS if pulmonary parenchymal or pleural cavity hemorrhage
tachypnea
dyspnea
sometimes coughing
CS if pericardial sac hemorrhage
dyspnea
collapse
CS if abdominal cavity hemorrhage
discomfort/enlargement of the the abdomen
CS of joint hemorrhage
lameness
CS of eye hemorrhage
sudden blindness
CS of GI tract hemorrhage
hematemesis
melena
hematochezia
CS of brain/spinal cord hemorrhage (rare)
CNS signs
What is the primary treatment for anticoagulant rodenticide? How long should it be given?
Vitamin K1
- SQ injection of K1 for first 24hrs
- after that, oral tablet of K1
- treat for 7-10 days if first gen.
- treat for at least 30 days if second gen.
- recheck clotting profile 2-3 days after the last dose of vitamin K1 has been given
Why should vit. K not be given IM or IV?
IM = may lead to deep muscular hematoma and ongoing hemorrhage in the muscle IV = can cause anaphylactic reaction
What treatments may be done in clinic in addition to vitamin K?
Whole blood or plasma transfusion
- both contain clotting factors
- whole blood also contains RBCs that will increased O2 carrying capacity
If pericardial sac or pleural cavity hemorrhage, a pericardiocentesis or thoracocentesis could be done, but you have to weight the odds of removing the blood already there vs. initiating more hemorrhage
How is rodenticide coagulopathy identified?
- ask questions about Hx/environment if anemia on CBC
- notice if venipuncture site keep bleeding
- evaluation of a clotting profile
What tests are in a clotting profile? What will the results likely be if anticoagulant rodenticide is at work?
- Prothrombin Time (PT)
- Activated Partial Thromboplastin Time (PTT or APPT)
- Activated Clotting Time (ACT)
- Clotting times will be prolonged
- PT will be prolonged first because it primarily assesses clotting factor VII, the factor with the shortest half life
Precautions for handling anticoagulant rodenticide patients
- avoid anything that will initiate bleeding
- avoid excessive struggle that could activate bleeding again
- use needles and catheters that are the smallest gauge possible
- use peripheral blood vessels if you need to get blood and wrap it with a pressure wrap afterward
- cage rest for several days
Where should you never draw blood from if the pet has a clotting disorder?
jugular vein
What are the 4 vitamin K dependent coagulation facotrs?
IX (intrinsic)
VII (extrinsic)
X & II (common)
