Pet First Aid: Warfarin Poisoning

Warfarin is one of several compounds that may be used in rodent poisoning. Many dogs and cats (especially farm pets) are poisoned by warfarin each year — either from eating the rodent bait or by eating a rodent that has eaten the bait. This is the most common cause of poisoning in pets.

Warfarin causes internal bleeding because it blocks the body’s production of clotting agents — proteins that allow the blood to clot. The body has a supply of clotting proteins already, so it may take a day or two after the poison has been ingested for symptoms to develop.

Symptoms of warfarin poisoning:

  • Bleeding from the mouth or nose.
  • Bleeding from the anus.
  • Blood in urine or stool.
  • Internal bleeding.

Your veterinarian will need to see your pet as soon as possible after you realize he has ingested rat poison. Bring the packaging for the bait, if you have it, so the vet can see exactly what has been eaten. Not all rat poisons contain warfarin, but all rat poisons can be deadly to pets. Warfarin poisoning is often treated with doses of vitamin K, which helps restore the blood’s ability to clot. You may be giving your pet oral doses of vitamin K for several weeks after the incident.

If you catch your pet in the act of eating rat poison, you’ll need to induce vomiting. Use a needleless syringe or even a turkey baster to squirt 3% hydrogen peroxide solution into the back of your pet’s mouth. Give between one and two teaspoons of solution for every ten pounds of weight — so a 100 pound dog would need between ten and twenty teaspoons in a dose. Give the hydrogen peroxide, then wait five or ten minutes to see if your pet vomits. If he does, take him to the vet right away. If not, administer another dose.