Toxicity to pets

Long-acting anticoagulants (LAACs) are the most common and well known type of mouse and rat poisons. This type of poison prevents the blood from clotting, resulting in internal bleeding. Long-acting anticoagulants work similarly to the “blood thinner” medications that people take (e.g., warfarin or Coumadin®). When dogs or cats ingest LAACs, it typically takes 3-5 days before signs of poisoning are visible. However, if the pet has been chronically exposed to the product, the onset of clinical signs may be sooner. Common signs of poisoning include signs of internal bleeding: lethargy, exercise intolerance, coughing, difficulty breathing (due to bleeding into the lungs), weakness, and pale gums. Less common signs include vomiting, diarrhea (with or without blood), nose bleeds, bruising, bloody urine, swollen joints, inappetence, and bleeding from the gums.

Fortunately, this specific type of mouse and rat poison does have a prescription antidote called Vitamin K1. Over-the-counter medications or food with high vitamin K content will not be sufficient substitutes. Most pets need to be treated with Vitamin K1 for 30 days. Two days after the last dose of Vitamin K1 is administered, a blood clotting test called a prothrombin (PT) should be checked to make sure the clotting is normal; otherwise, your pet can still potentially bleed out despite one month of therapy!

The dose needed to cause poisoning from LAACs varies greatly between active ingredients and species of animal. With some types (e.g., brodifacoum), it only takes a very small amount to cause poisoning, especially in dogs. Other types have a wider margin of safety (e.g., bromadiolone) and it takes a larger amount to cause poisoning. In general, cats are typically quite resistant to the effects of LAACs and often require a much higher dose than dogs to cause poisoning. The age and health of the pet may be another factor determining whether or not the amount ingested will be poisonous. Animals with underlying liver or gastrointestinal disease, as well as the very young or very old, are more at risk.

If you suspect your dog or cat were exposed to mouse and rat poison, call your veterinarian or Pet Poison Helpline® immediately for life-saving treatment recommendations.