Why Is Bromethalin So Deadly?
Bromethalin is a neurotoxin that affects cells in the brain and liver. It causes sodium accumulation within cells and results in fluid buildup within the brain.
Bromethalin poisoning is fast acting -- signs of brain swelling and central nervous system disturbance can appear within 2 to 24 hours after ingestion. The swelling compresses nerves, which then lose their ability to send messages. Depending on how much poison has been ingested, symptoms can include unsteadiness, weakness, muscle tremors, paddling motions of the limbs, hyperexcitability, depression, vomiting, high fever, stiffness in the front legs, and seizures.
With anticoagulant toxicity, veterinarians typically have from about 3 days to a week to save the patient, but the rapid onset of bromethalin poisoning leaves almost no time for error. Once an animal is showing neurological symptoms, effective treatment becomes more difficult and costly, and the pet may only have a day or two to be saved. Even in cases for which treatment is successful, more emergency care and hospitalization is involved than in cases of anticoagulant poisoning.
Because there’s no antidote for bromethalin, decontamination (inducing vomiting and administering activated charcoal) is the primary treatment. But according to Dr. Brutlag, not enough veterinarians are familiar with how to neutralize exposure to this toxin.
The severity of intoxication depends on how much bromethalin is ingested. If a pet is discovered within 10 to 15 minutes of ingestion, the owner can induce vomiting. But beyond that very short window of time, vomiting should only be induced in a veterinary setting -- and the pet must then be monitored for acute signs of neurological impairment and given repeated doses of activated charcoal over a 24-hour period.
“Should clinical signs arise,” says Dr. Brutlag, “patients are treated with standard measures to reduce cerebral edema [swelling in the brain] including IV fluids, mannitol, etc.” A pet who has recurrent seizures or paralysis after ingesting bromethalin has a poor prognosis.