Which of the following is listed as a single-dose anticoagulant rodenticide?

• A. Bromethalin
• B. Zinc-phosphide
• C. Bromadiolone
• D. Vitamin D3

Answer: (C)

Single-dose anticoagulant rodenticides work by directly disrupting the vitamin K cycle, so a rodent can die after a single feeding from excessive internal bleeding due to lack of clotting factors. Bromadiolone is a classic example of this class: it’s a potent second-generation anticoagulant that inhibits vitamin K epoxide reductase, depleting active clotting factors II, VII, IX, and X and causing fatal hemorrhage after limited exposure.

Bromethalin, in contrast, is a non-anticoagulant neurotoxin that disrupts mitochondrial energy production in the nervous system, leading to paralysis and death without involving the vitamin K pathway. Zinc phosphide releases phosphine gas in the stomach, causing systemic toxicity through cellular respiration disruption, not through anticoagulant mechanisms. Vitamin D3 rodenticide kills primarily by inducing dangerous hypercalcemia and renal failure, also not via anticoagulation.

So bromadiolone is the correct choice because it specifically fits the criteria of an anticoagulant that can be effective after a single exposure, whereas the others operate by different toxicological mechanisms.