Rodenticide Toxicity

Question 1

What are the four main types of anticoagulant rodenticide?

Answer 1

• Warfarin
• brodifacoum
• bromdialone
• diphacinone (indandione)

Question 2

What is the specific mechanism of action of anticoagulant rodenticides?

Answer 2

• inhibiting Vitamin K1 epoxide reductase

Question 3

What blood test will a change be seen in first after anti-coagulant rodenticide poisoning and how long will it take to see a change?

Answer 3

• PT time - 36-72 hours for Factor VII (shortest half-life)

Question 4

Describe the four main steps to approaching a recent known ingestion of anticoagulant rodenticide poisoning:

Answer 4

1. Emesis if <2-4 hours
2. Activated charcoal - less than 8-12 hours
3. Treat with Vitamin K for 4 weeks
4. Check PT for 48-72 hours after the completion of Vitamin K1 therapy

Question 5

For Bromethalin Rodenticide:

1. Describe the mechanism of action
2. Describe the physiology involved and clinical signs
3. How would you treat it?

Answer 5

1. Inhibits oxidative phosphorylation and ATP production
2. Loss of ability to maintain an osmotic gradient → cerebral oedema (neuro signs) + ascending paralysis beginning in the forelimbs
3. If acute → GI decontamination (treat for seizures + increased intracranial pressure - use mannitol and/or frusemide to decrease cerebral oedema)

Question 6

For cholecalciferol rodenticide:

1. Describe the toxic principle
2. What is the most important clinical sign?
3. How is a diagnosis made?
4. State four treatments that you may provide

Answer 6

1. Converted to Vitamin D → severe hypercalcaemia + hyperphosphatemia
2. Acute renal failure
3. Known exposure or hyperphosphatemia + hypercalcaemia + azotaemia

Treatment:

• Furosemide → promoting urinary Ca excretion
• Corticosteroids - decrease intestinal Ca absorption and urinary retention
• Bisphosphonates → inhibit osteoclast and bone re-absorption
• Calcitonin