Is Bromethalin safe for dogs and cats?

Bromethalin (N-methyl-2,4-dinitro-N-(2,4,6-tribromophenyl)-6-(trifluoromethyl)benzenamine) is a non-anticoagulant neurotoxic rodenticide increasingly common in the US since EPA restrictions on second-generation anticoagulant rodenticides for consumer use in 2011. Mechanism: uncouples oxidative phosphorylation in neural mitochondria → impaired myelin maintenance → cerebral and spinal cord edema → ascending paralysis. Critically: there is NO antidote for bromethalin. Minimum lethal dose in dogs: approximately 1–2 mg/kg (acute) to 5–10 mg/kg over multiple exposures. A single commercially available bait block may contain sufficient bromethalin to be lethal to a small or medium dog. Onset of clinical signs: 24–96 hours post-ingestion. Signs of acute/severe exposure: hind limb weakness, ataxia, ascending paralysis, tremors, hyperexcitability, opisthotonus, seizures, hyperthermia, death. Signs of subacute/lower-dose exposure: bilateral hind limb paresis, lethargy, vomiting — may persist for days to weeks. Diagnosis is often presumptive (bait product identification). Treatment is limited to aggressive decontamination (emesis + activated charcoal + cathartic — critical if within 1 hour of ingestion; activated charcoal for 24–48 hours due to enterohepatic recirculation), anti-edema measures (mannitol, corticosteroids — evidence limited), and supportive care. ASPCA APCC now receives more bromethalin calls than anticoagulant rodenticide calls in many regions.

Cats are highly susceptible to bromethalin toxicosis — the minimum lethal dose is approximately 0.45 mg/kg (lower than dogs), reflecting cats' higher lipophilicity of neural tissue and lower metabolic capacity for bromethalin hydroxylation. Clinical signs in cats often appear as hindlimb paresis, altered mentation, hypersensitivity to stimuli, and seizures at subacute doses. Cats' hunting behavior creates secondary poisoning risk from consuming poisoned rodents containing bromethalin in tissues. Unlike anticoagulant rodenticides, no bioassay-based antidote treatment exists; the prognosis for severely affected cats is poor even with intensive supportive care. Indoor cats with access to rodenticide bait stations and outdoor cats in treated environments (commercial buildings, farms, urban rodent control programs) are both at risk. ASPCA strongly advises keeping bromethalin products inaccessible to cats and checking product labels before purchase, as bromethalin products are visually similar to anticoagulant products and owners may not distinguish them.