08 Mar Flocoumafen – The Super Potent Superwarfarin
Most veterinarians in Australia will be very familiar with treating anticoagulant rodenticide ingestions. The LD50 for long acting second generation anticoagulant rodenticides is generally much lower than for first generation anticoagulant rodenticides such as warfarin.
In performing a risk assessment for all long acting anticoagulant rodenticide (second generation) ingestions, the Animal Poisons Centre recommends veterinary intervention (ie, gastrointestinal decontamination where appropriate and further investigation or antidotal therapy) at ingested doses of 0.02 mg/kg or greater. This intervention dose has a margin of safety built into it, and is based on one tenth of the lowest reported LD50 of brodifacoum which is 0.2 mg/kg.
Enter flocoumafen, the super potent superwarfarin. Flocoumafen is the only anticoagulant rodenticide in Australia that has a canine LD50 lower than brodifacoum. The reported oral LD50 of flocoumafen in dogs is 0.075 mg/kg, and therefore the Animal Poisons Centre recommends an intervention dose of 0.0075 mg/kg for this highly potent rodenticide.
Whilst flocoumafen exposures are not particularly common, it is found at a concentration of 0.05 g/kg in brands such as Storm and Stratagem. In a 10 kg dog, an ingested bait dose as low as 1.5 g (one point five grams) could result in a coagulopathy and requires intervention. For this reason, the Animal Poisons Centre recommends extreme caution when dealing with flocoumafen exposures and it would be reasonable to decontaminate all exposures (other than a taste or lick).