Rodenticide Toxicity: How Does Rat Poison Work?

Rodenticides are designed to be highly palatable, making bait an appealing snack for pets. Many types of poison can cause illness, even at low doses. If your pet finds and ingests any amount of rodenticide, they’re at risk. Most cases of rodenticide toxicity occur when pets eat pure bait they find in traps or storage.

Rodenticides and Relay Toxicosis (Secondary Poisoning)

When animals eat prey that have ingested or died from rodenticide, there’s still some risk of rodenticide toxicity. This secondary poisoning is known as “relay toxicosis.” Typically, rodents that died from rodenticide poisoning don’t pose a huge risk when ingested. This is because the rodent has already metabolized much of the poison. However, sometimes pets kill and eat prey that have ingested rodenticide but haven’t died from the toxin. This can be more dangerous for your pet. Err on the side of caution and get your pet checked out if you have any concerns.

Eating one dead, poisoned rodent is unlikely to cause issues; animals that repeatedly prey on rats and mice that have eaten bait can find themselves in trouble. The toxic chemicals can build up over time. This is most often seen in wildlife, such as raptors, but can also be an issue with barn cats and other household pets.

Audio Article: How Does Rat Poison Work?

How Does Rat Poison Work?

Many rodenticides are marketed as being safe to use around pets. Unfortunately, this isn’t usually the case. How does rat poison work on pets? Each family of rodenticides has its own risks and treatment methods.

Anticoagulant Rodenticides

Anticoagulant rodenticides are some of the most common baits. This class of poisons works by preventing the target’s blood from clotting, causing them to bleed. Anticoagulant toxicities can take days to produce symptoms. This makes it difficult to track down why your pet is sick. Symptoms of anticoagulant rodenticide toxicity include bruising, bleeding from the nose or ears, bloody stool, bloody urine, a swollen abdomen, and weakness. Luckily, anticoagulant rodenticides are treatable if the toxicity is diagnosed in time. Vitamin K therapy, repeat bloodwork, and supportive care can prevent illness if the treatment is started soon after your pet eats the bait. But be aware that anticoagulant rodenticides have been shown to build up over time in animals that prey on poisoned rodents and can cause a lot of harm to wildlife via relay toxicosis.

Bromethalin Rodenticides

Bromethalin rodenticides are also commonly used to control rodent populations. Bromethalin kills rodents by causing swelling in the brain. This causes neurological symptoms, including tremors, seizures, and death. Symptoms begin rapidly after ingestion, typically within four hours. Often, symptoms can last for days and can even be permanent. Unlike anticoagulant rodenticides, there are no direct treatments. Instead, bromethalin toxicities must be treated supportively. Relay toxicosis is possible but not common with bromethalin rodenticides.

Phosphide Rodenticides

Phosphide rodenticides, including zinc, calcium, and aluminum phosphide, have been on the market for over 100 years. These poisons work by reacting with gastric fluids to produce corrosive gases. Phosphine gases damage the lining of the gut and then move on to damage your pet’s organs, especially the brain, liver, and heart. Phosphide poisoning occurs quickly, with serious symptoms occurring in as few as 15 minutes. If you suspect your pet may have gotten into a phosphide-based rodenticide, be cautious while handling or transporting them. Even secondhand, the gases can cause serious harm to humans when inhaled. It’s possible for relay toxicosis to occur with phosphide rodenticides.

Cholecalciferol Rodenticide

Cholecalciferol rodenticide is the newest addition to the world of rat baits. This class of poisons uses vitamin D3 to kill rodents by disrupting the balance of calcium and phosphorus in the body. By disrupting this balance, cholecalciferol rapidly damages the kidneys, leading to death. Signs and symptoms can take up to two days to emerge, at which point irreversible damage has already occurred. Cholecalciferol toxicity is also extremely challenging to treat. Rapid decontamination is essential if your pet has been exposed to this poison. Cholecalciferols haven’t been shown to cause acute relay toxicosis, but they can build up in animals’ systems and make them sick if they continue to eat poisoned prey.

Several other poisons can be used to control rodent populations, including strychnine and corn-gluten rodenticides. Remember that no rodenticide is completely safe for your pets or backyard animals. If you’re concerned your animal may have been exposed to rodent bait, contact your veterinarian.

My Dog Ate Rat Poison, Now What?

If you know that your dog ate rat poison, act fast. Call your veterinarian or closest emergency animal hospital immediately. Veterinarians are the experts at treating toxicities in pets, and they’ll be able to give you the best advice. You may also be asked to call a poison control hotline. The veterinary toxicologists who work for these hotlines have up-to-date information about dosages and treatments and will work with your veterinarian to provide the best care possible.

The first step to treating rodenticide toxicity is decontamination. This means removing as much of the toxin from your pet as possible. Sometimes your veterinarian may recommend starting this process at home by attempting to make your pet vomit. Only induce vomiting if your veterinarian has asked you to do so. Risks to inducing vomiting at home include damage to the lungs and choking. Exposure to phosphide rodenticides can be harmful to humans and must be dealt with carefully.

Each rodenticide family requires unique treatments. This means it’s important your veterinarian knows exactly what your pet has gotten into. If you can, bring the packaging or a photo to your vet so they have all the information they need to provide the best care. Rodenticides can look similar but behave differently. If you keep rodenticide around your home or farm, write down what rodenticide you’ve placed and keep track of the quantities. That way, you’ll have as much information as possible in an emergency.

Rat Poison Alternatives for Pet-Safe Rat Control

No one wants to end up in the emergency room with a poisoned pet. Reducing or eliminating your use of rodenticides with other methods of pet-safe rodent control cuts off the problem at the source. Your creatures certainly can’t ingest any poisons if they’re nowhere to be found. Instead of using poisons to control your rodent population, try this three-step method to keep unwanted pests at bay.

• Avoid attractants. This means getting rid of or securing anything that might entice rats and mice. In your home, keep food in sealed containers and clean up food waste quickly. This means no dirty dishes in the sink and frequent trips to take the trash out. Outside, keep your compost covered and secure grain sources as best you can. Brush piles and tall grasses can offer shelter to rodents and encourage them to take up residence near your home. Netting or caging your plants can also reduce the rodent presence on your property.
• Introduce deterrents. This includes anything that will scare rodents away from your spaces or prevent them from entering. Sealing off cracks and openings to your home or barn can make a huge difference. Other deterrents include lights, sounds, and scents that are unpleasant to rodents. Fake owls are a common deterrent, although their impact can be limited. It doesn’t take most animals long to learn the fake bird can’t actually eat them. Instead, try tools like high-intensity strobe lights, mint oils or plants, whole cinnamon or clove, or cayenne pepper sprays. You can also opt for nontoxic traps, like snap, CO2, or electric traps, or catch-and-release methods.
• Invite predators to your space. While it might sound unwise, it’s truly a logical solution. To reduce your rodent population, invite raptors, the natural predators of rodents. Raptor boxes are one of the best ways to facilitate nature’s pest control. Organizations, such as Raptors Are the Solution (RATS) and the Hungry Owl Project, advocate for adding nesting boxes and planting oak trees to attract owls and other birds of prey to your property. In a three-year study of barn owls in California, researchers found that owls had a much lower cost per rodent than rodenticides.

If you must use rodenticides, do so safely. Always follow the safety instructions on the packaging of any baits you buy. Restrict access to traps and to wherever you store extra bait. Remember, these baits are made to taste and smell delicious, and your pets may find them, even if your traps are concealed. Restrict trap use to interior places that aren’t accessible to your pets or other predators. You can also use a snap trap inside bait boxes to prevent poisoned rodents from exiting the trap and being eaten. Most importantly, keep track of what baits you use and ask your neighbors what they have around. That way, if the worst does occur, you’ll be armed with the best information to protect your pet.

Amelia Eigerman is an emergency room veterinary technician with a passion for science communication. In their time working at multiple emergency hospitals, Amelia has helped treat many dogs suffering from rodenticide toxicity. They hope to help pet owners learn more about how to keep their animals safe and what to do when things go wrong.