The risks of rodenticides

sad dog

Rodenticides have long been used for population control of mice, rats and other rodents. Historically, anticoagulant baits have been most popular. Anticoagulants cause inhibition of blood clotting, leading to excessive, fatal bleeding.

In 2013, the EPA banned anticoagulant rodenticides in an attempt to decrease toxicity to children, pets and wildlife. A phase-out program was initiated, and by 2015 companies were no longer able to manufacture or distribute these type of rodenticides. Stores that had remaining stock were able to sell the product until the supply was completely depleted.

Now, these products are no longer commercially available but may be found in many homes from previous purchases.

This is important because not all rodenticides are the same or carry the same risks. While the anticoagulant rodenticides carried a high toxicity, an antidote was widely available. The newer products require a large dose for toxicity to occur but no antidote is available. Because of this, if you use any rodenticides, it is extremely important that you know which product you are using, keep your pet away from the product and if they do ingest some, seek veterinary attention immediately.

The most commonly used rodenticides fall into the following categories:

Anticoagulants 

Active ingredients: Warfarin, brodifacoum, bromadiolone, diphacinone.

Clinical signs: Bleeding, pale gums, weakness, exercise intolerance, coughing, swollen joints and lameness. (Clinical signs can be delayed by 2–3 days after ingestion.)

Treatment: Vitamin K, blood transfusions and, in severe cases, hospitalization.

Bromethalin

This is a neurotoxin that stops cells in the brain from producing energy. This causes the nerves to swell, which puts pressure on the brain.

Clinical signs: Muscle tremors, seizures, hyperexcitability, ataxia (incoordination), central nervous system depression, weakness, paralysis and death. (Clinical signs may occur 24 hours to 2 weeks after ingestion.)

Treatment: There is no antidote for this product. Treatment includes decontamination of the stomach and IV fluids.

Cholecalciferol

This rodenticide causes too much calcium to be absorbed from the kidneys and gastrointestinal tract, resulting in an excess of calcium in the blood. This can lead to kidney failure, heart abnormalities, central nervous system abnormalities and tissue mineralization.

Clinical signs: Vomiting, diarrhea, depression, marked increase in water consumption and urination, heart arrhythmias and weakness.

Treatment: Aggressive decontamination, IV fluid support for kidneys, drugs to inhibit bone resorption and other supportive care. Treatment may last several weeks, and surviving patients will have permanent kidney and muscle damage.

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