Rodenticide Coagulopathy

Question 1

What happens during primary hemostasis? What are the 2 key players?

Answer 1

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

Question 2

What happens during secondary hemostasis? What are the 2 main types of players?

Answer 2

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

Question 3

Define coagulopathy

Answer 3

a disease or condition affecting the blood’s ability to coagulate or form a clot to stop hemorrhage from ocurring

Question 4

What is the purpose of anticoagulant rodenticide? How are pets exposed to it?

Answer 4

• 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

Question 5

What does anticoagulant rodenticide do to the coagulation pathway?

Answer 5

• 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

Question 6

First vs second generation rodenticide

Answer 6

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

Question 7

When do clinical signs appear?

Answer 7

12-24hrs post ingestion because the body has some vitamin K that’s already been made but not yet used

Question 8

Clinical signs of anticoagulant rodenticide

Answer 8

• Anemia (lethargy, weakness, depression) due to hemorrhage

- Other clinical signs depend on hemorrhage location

Question 9

CS if pulmonary parenchymal or pleural cavity hemorrhage

Answer 9

tachypnea
dyspnea
sometimes coughing

Question 10

CS if pericardial sac hemorrhage

Answer 10

dyspnea

collapse

Question 11

CS if abdominal cavity hemorrhage

Answer 11

discomfort/enlargement of the the abdomen

Question 12

CS of joint hemorrhage

Answer 12

lameness

Question 13

CS of eye hemorrhage

Answer 13

sudden blindness

Question 14

CS of GI tract hemorrhage

Answer 14

hematemesis
melena
hematochezia

Question 15

CS of brain/spinal cord hemorrhage (rare)

Answer 15

CNS signs

Question 16

What is the primary treatment for anticoagulant rodenticide? How long should it be given?

Answer 16

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

Question 17

Why should vit. K not be given IM or IV?

Answer 17

IM = may lead to deep muscular hematoma and ongoing hemorrhage in the muscle
IV = can cause anaphylactic reaction

Question 18

What treatments may be done in clinic in addition to vitamin K?

Answer 18

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

Question 19

How is rodenticide coagulopathy identified?

Answer 19

• ask questions about Hx/environment if anemia on CBC
• notice if venipuncture site keep bleeding
• evaluation of a clotting profile

Question 20

What tests are in a clotting profile? What will the results likely be if anticoagulant rodenticide is at work?

Answer 20

• 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

Question 21

Precautions for handling anticoagulant rodenticide patients

Answer 21

• 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

Question 22

Where should you never draw blood from if the pet has a clotting disorder?

Answer 22

jugular vein

Question 23

What are the 4 vitamin K dependent coagulation facotrs?

Answer 23

IX (intrinsic)
VII (extrinsic)
X & II (common)