Rodenticide, commonly used to kill rats, mice, moles and gophers, comes in many forms and can cause a variety of serious problems in our pets.

Rodenticide containing cholecalciferol (Vitamin D) causes high calcium levels in the blood and can damage the kidneys, central nervous system, heart and intestines. Poisons that contain bromethalin are neurotoxic, causing paralysis and possibly coma, and brodifacoum, warfarin and other anticoagulant rodenticides cause an inability to clot the blood and often lead to internal bleeding.

There is no question that rodenticide is dangerous for our pets, but according to the February issue of DVM Newsmagazine, one form in particular—zinc phosphide—can also create toxic gas that is harmful to humans.

This type of rodenticide is available as a powder or grain-based pellet and is sold under several trade names, including Arrex, Commando, Dexol, Kilrat, GophaRid, Phosvin, Ridall, Ratol and Sweeney's Poison Peanuts.

When ingested, zinc phosphide forms a poisonous gas when it comes in contact with water. This means that if a pet eats this particular type of rodenticide and later vomits, the gas will be released, posing a serious risk to humans who might inhale it.

According to the magazine, “the suspected expelled gas—phosphine gas—is colorless, flammable and explosive at ambient temperature and smells like garlic or decaying fish.”

Symptoms of inhalation in humans include diaphragm pain, nausea, vomiting, excitement and a smell of phosphorus on the breath. Exposure to high concentrations can also cause weakness, bronchitis, pulmonary edema, shortness of breath, convulsions and even death.

We strongly encourage our clients to avoid using rodenticide. If you suspect that your pet has ingested rodenticide of any kind, please seek veterinary care immediately.

If your pet vomits at home after ingestion of zinc phosphide-based rodenticide, please follow these guidelines:

  • If possible, have the animal vomit outside where there is plenty of ventilation and the area can be hosed down. If your pet has already vomited indoors, remove all people and pets from the area and ventilate. Most local fire departments can measure the level of phosphorine in the air and determine when the area is safe to reenter.
  • After vomiting has occurred, stand upwind of the animal and bring the animal upwind of the vomit.
  • Do not lower your head down to the animal. Since phosphine gas is heavier than air, it will be more highly concentrated closer to the ground.
  • Flush the area with copious amounts of water while standing upwind. All vomit may be washed down a storm sewer or off a hard surface onto grass. There will be enough ventilation outside to prevent the phosphine from reaching harmful levels.
  • Seek medical attention immediately if you experience any symptoms upon exposure to phosphine gas.