Rat Bait Poisoning in Dogs

There are several types of rodenticides available, with the most common being anticoagulant rodenticides. These products interfere with the body’s normal blood-clotting process. Pets may develop primary poisoning after directly eating bait, or secondary poisoning if they consume a rodent that has ingested the toxin (although in most cases, multiple poisoned rodents would need to be eaten for toxicity to occur).

To understand how this happens, it helps to know a little about vitamin K1. Vitamin K1 is essential for the production of clotting factors that allow blood to clot properly. Anticoagulant rodenticides block an enzyme responsible for recycling vitamin K1, which gradually depletes the body’s ability to form clots. As a result, bleeding can occur internally or externally, sometimes several days after exposure.

Anticoagulant rodenticides are divided into two main groups:

• First-generation anticoagulants (e.g. warfarin, coumatetralyl, diphacinone) are considered “multi-dose” products, meaning they usually need to be eaten over several feedings to reach a lethal dose. They act more slowly and are cleared from the body more quickly, making them generally less potent than second-generation products.
• Second-generation anticoagulants (e.g. brodifacoum, bromadiolone, difethialone, difenacoum, flocoumafen) are “single-dose” products, meaning a potentially lethal amount can be consumed in just one feeding. These are more potent, persist in the body for much longer, and carry a higher risk of secondary poisoning. If a pet ingests a second-generation rodenticide, treatment is typically required for a longer period due to their prolonged effects.