Rodenticide poisoning is one of the most common poisonings that we see on an emergency basis. There are three main types of poisons used: anticoagulants, neurotoxins, or Vitamin D-containing compounds. One of the most prevalent anticoagulant rodenticides that has been used is d-CON, but there are numerous other manufacturers. Rodents have become more resistant to some of these drugs, and the EPA has placed a ban on many of these anticoagulant products. As a result, other rodenticides, such as the neurotoxin, bromethalin, are being used more commonly to replace anticoagulants.
Bromethalin’s primary effect causes changes that result in cerebral edema or fluid accumulation in the brain. Bromethalin poisoning is dose-dependent, and cats are even more sensitive to the toxic effects – meaning a smaller ingested amount is even more harmful than in dogs. At high doses, signs can develop within 4-36 hours after ingestion. Dogs often exhibit a convulsant syndrome consisting of tremors, hyperexcitability, and seizures. Dogs that ingest a lower toxic dose more often develop a paralytic syndrome 1-5 days later, beginning with weakness of the hind limbs and incoordination that progresses to paralysis of the hind limbs and depression that may ultimately result in a coma. Cats appear to more commonly develop the paralytic syndrome, and they may also get a distended abdomen.
Unfortunately, there is no test for bromethalin poisoning, making a diagnosis without a history of bait ingestion more difficult. Diagnosis is dependent upon a history of ingestion of poison, coupled with development of the above progressive neurological signs in an appropriate time framework.
Treating This Poison
Unlike the anticoagulants, there is no antidote for this poison. Because the poison is rapidly absorbed (peak levels in four hours) and slowly excreted, prompt treatment in the first few hours is very important to success.
The first step is inducing vomiting to remove as much of the poison as possible if the pet has recently ingested the poison. Second, to reduce further absorption of the toxin, repeated doses of activated charcoal are administered. Finally, if the pet is exhibiting signs of toxicity, treatment is directed towards supportive symptomatic treatment, which may include medications to control seizures and providing nutritional support and basic nursing care. Pets that are paralyzed or having seizures have a poor-to-grave prognosis, even with aggressive treatment.
Take No Chances
Since the active ingredient cannot be determined from the bait’s color or physical appearance, identifying the type of rodenticide from the package label is important in distinguishing which type of rodenticide has been ingested to treat successfully. If your pet has ingested a rodenticide, keep the container/box listing the ingredients to bring in, and contact a veterinarian as soon as possible for further recommendations. The ASPCA also has an animal poison control hotline: 888-426-4435; there is a $65 consultation fee.
Written by: Larry Jacobs, DVM