How Rat Poison Works

Most rodenticides on the market are comprised of anticoagulant compounds. Once ingested, the poison prevents blood clots from forming, resulting in excessive internal bleeding.

Whereas some rat poisons are lethal after just one exposure, others require multiple doses to kill. These usually take four to 14 days of a rodent feeding on them for death to occur.

Secondary poisoning is an issue that largely affects wildlife, farm animals, and pets as well. An example of this is when a household cat eats a mouse that has been poisoned with rodenticide.

Here’s how they work:

  • Anticoagulants cause internal bleeding that may go unnoticed for several days after exposure. Signs of poisoning in pets include trouble breathing, lethargy, seizures, shaking, bloody stool, bleeding from the gums, and abdominal swelling.
  • Bromethalin is a neurotoxin that causes cell death in the central and peripheral nervous systems. A pet that has eaten bromethalin may vomit, have seizures, lose control of their legs, or fall into a coma, beginning eight to 12 hours after exposure.
  • Cholecalciferol is a form of vitamin D that leads to calcium toxicity, kidney damage, and heart failure. Signs of poisoning in pets include loss of appetite, vomiting, frequent urination, and depression, beginning 12 to 36 hours after exposure.
  • Zinc phosphide is a substance that turns to gas inside the body once consumed, crippling the body’s major organs. Signs of toxicity in pets include anxiety, pacing, weakness, and convulsions, beginning four to 18 hours after exposure.
  • Strychnine is a compound that triggers seizures so severe that they inhibit breathing. In animals, seizures are the primary symptom, beginning 15 minutes to two hours after exposure.

Ingestion is not the only form of exposure. With the exception of warfarin, all rodenticides are highly toxic when ingested or inhaled. Warfarin is also highly toxic when ingested, but there is low toxicity associated with touching or inhaling it.

Diphacinone, bromadiolone, brodifacoum, and bromethalin are toxic to touch, as they are absorbed into the skin. Take caution to protect your eyes when working with rodenticides; most can cause mild to moderate eye irritation.