Anticoagulant rat and mouse poisons in Pets

Rat bait anticoagulants cause bleeding 3–7 days after eating. Convert grams of 0.005% bait to milligrams of active ingredient and learn why the quiet first days are the time to act.

What It Is

Anticoagulant rodenticides such as brodifacoum, bromadiolone, difethialone and the older warfarin stop the liver from recycling vitamin K, which the body needs to make clotting factors. Bleeding starts only after the existing clotting factors are used up, so a poisoned pet looks normal for several days.

Where Pets Come Across It

Bait blocks, pellets and grain baits set for rats and mice in sheds, garages and lofts, and sometimes moved by rodents into new places. Pets can also be poisoned by eating a poisoned rodent, though this rarely delivers a large dose.

Which Animals Are Affected

Dogs most often, cats less often. Birds and wildlife, especially owls and foxes that eat poisoned rodents, are also affected.

Published Toxic Dose

Thresholds differ by compound. The Merck Veterinary Manual explains that toxic doses for pets are usually estimated as one-tenth of the lowest reported LD50 for that ingredient and species, and that second-generation products are 2.5 to 200 times more potent than first-generation ones. Most household baits contain 0.005% active ingredient, which is 0.05 mg per gram of bait, so the poison line needs the exact ingredient and the grams eaten. Because the threshold depends on the product, the calculator gives no risk level on this page.

Signs and How Soon They Appear

Merck notes that clotting tests rise 2 to 5 days after eating bait and bleeding usually appears 3 to 7 days after a toxic dose. Look for lethargy, pale gums, coughing or breathing difficulty (bleeding into the chest), nosebleeds, blood in urine or stools, bruising and swollen joints.

What to Do Right Now

Call your vet or a poison line now, even if your pet seems well; the silent period is when treatment is easiest. Bring the bait packaging or a photo of the label with the active ingredient. Do not induce vomiting at home.

Frequently Asked Questions

Sources and References

• Merck Veterinary Manual: Anticoagulant Rodenticide Poisoning in Animals
• ASPCA Animal Poison Control Center

Related Poisons