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About Eric Barchas, D.V.M.

Eric Barchas, DVM is a veterinarian who lives and works in the San Francisco Bay Area. His emphasis is on small animal medicine, emergency medicine, hospice and wellness. An avid traveler, he has studied lions in Botswana and salmon in southern Chile.

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Rodenticide (Mouse or Rat Poison) Toxicity in Cats and Dogs

Animals Affected

Primarily dogs; occasionally cats

Overview

Mouse and rat poisons (known as rodenticides) are commonly used by individuals and exterminators in homes and businesses.  Although the poisons are designed to control pests, they are toxic to dogs and cats as well.  Several varieties of rodenticide are commercially available.  This article covers the most commonly used rodenticides, which work by preventing blood from clotting.  These compounds are called anticoagulant rodenticides.  Examples of anticoagulant rodenticides include d-CON® and Talon®.

Animals that consume anticoagulant rodenticides lose blood into the environment or internal body spaces such as the lungs.  If they do not receive veterinary attention, they will become sick and almost certainly die from the consequences of continuous bleeding.

An antidote to the poisons is available.   It must be administered for four to eight weeks.  In most cases, the antidote is effective in preventing illness and death from rodenticide toxicity.

Although anticoagulant rodenticides remain in common use, new regulations (as of 2015) in the United States will cause them to become markedly less common in the future.  They will be phased out, and replaced with an ingredient called bromethalin, which also is toxic to cats and dogs.  More information on bromethalin is available at the end of this article.

Symptoms of Anticoagulant Rodenticide Ingestion

Pets do not show symptoms for the first 72 - 96 hours after they consume anticoagulant rodenticides.  However, if a pet is known or suspected to have consumed rat or mouse bait, treatment should be implemented immediately (see below).

After the initial 72 - 96 hour window has passed, symptoms begin to develop.

  • Bleeding is a common symptom of exposure to anticoagulant rodenticides.     Pets may bleed from their skin, gums, ears, nose, eyes, or other locations.  Blood may be noted in urine, feces, or saliva.  Blood may be noted on carpet or furniture in areas where the pet spends time.
  • Bruising may occur as blood leaks into the skin.
  • Blood loss often leads to weakness, lethargy, and decreased appetite.
  • Bleeding into the lungs may lead to coughing (cats, dogs) or trouble breathing.
  • The abdomen may become distended and rounded if blood fills it.
  • Pale or white gums occur in animals that have lost significant amounts of blood.
  • Signs of shock, including collapse, loss of consciousness, decreased respiratory rate and decreased heart rate occur when blood loss is severe.

Risk Factors

  • The presence of rodenticides in the animal's environment is the leading risk factor.
  • Conventional wisdom among veterinarians holds that pets, especially cats, can suffer from rodenticide toxicity after consuming rodents that have been poisoned. Some experts doubt that this happens often.

Complications

Most animals that consume anticoagulant rodenticides will die unless they are treated by a veterinarian.

Diagnosis

In some instances, owners witness or suspect the consumption of rodenticide by their pet. In these cases, treatment for rodenticide toxicity is recommended.

When there is no known or suspected history of rodenticide consumption, blood tests that measure clotting ability can aid in diagnosis.  X-rays may be performed in pets that suffer from respiratory irregularities or abdominal distention.

Treatment

An antidote to anticoagulant rodenticides, vitamin K1, is readily available.  All pets that are diagnosed with anticoagulant rodenticide toxicity must receive the antidote once or twice daily for a period of 4 - 8 weeks. Vitamin K1 can be administered orally or by injection.

Veterinarians may cause a pet to vomit if they suspect that rodenticide is present in the animal's stomach.  Treatment with vitamin K1 is necessary even if most of the poison is eliminated in this fashion.

Any pet that shows severe symptoms of blood loss may require hospitalization and intensive treatments such as blood transfusions until its condition stabilizes.

Follow-up

Pets that receive veterinary attention within 72 hours of exposure to rodenticides often do not show any symptoms of poisoning.  However, most rodenticides remain in the body for four to eight weeks.  Therapy with vitamin K1 must be continued until this time period has elapsed.

Follow-up blood tests are necessary for most pets during and after treatment with vitamin K1 to ensure efficacy of treatment.

After a diagnosis of rodenticide toxicity, steps should be taken to ensure that pets do not have access to the poisons in the future.

Miscellaneous

The chemical names of some commonly used anticoagulant rodenticides include brodifacoum, difenacoum, diphacinone, chlorophacionone, coumachlor, warfarin, and indandione.

If a pet has consumed a rodenticide and the box or package insert for the product is in the owner's possession, the box or package insert should be made available to the veterinarian that treats the pet.

Anticoagulant rodenticides are toxic to humans as well as pets.

Pets sometimes consume the adhesive portion of glue traps that are designed to physically restrain mice.  Most glue traps do not contain toxic compounds.   Nonetheless, owners of pets that consume portions of glue traps should contact their veterinarian to confirm that no risk exists.

Bromethalin Toxicity in Dogs and Cats

As of 2015, anticoagulant rodenticides are being phased out of use in the United States.  They largely are being replaced by a different agent, bromethalin.

Bromethalin is a neurotoxin that causes brain swelling.  There is no antidote for bromethalin.  However, in general bromethalin is less deadly to cats and dogs than the anticoagulant products it has replaced.

Symptoms of bromethalin toxicity are neurological.  The first symptom is often uncoordination of the rear legs or agitation and exaggerated responses to environmental stimuli.  Vomiting, diarrhea, seizures, coma, and death are possible.  However, fatality is unlikely in most cases unless significant quantities of the product have been consumed.

There is no test for bromethalin, and its symptoms -- especially the early ones -- can mimic many other problems or toxicities (such as macadamia nut toxicity or metronidazole overdose).

Treatment for bromethalin toxicity is supportive.  IV fluids are often administered, and anti-seizure medications may be used.

Any dog or cat with known exposure to bromethalin should receive immediate veterinary attention.  Any dog or cat that displays neurological irregularities likewise should receive immediate veterinary attention.

Copyright © Eric Barchas, DVM. All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.