Is Methomyl safe for dogs and cats?

Methomyl is one of the most common causes of severe and fatal pesticide toxicosis in dogs in the US. The primary exposure vector is methomyl fly bait products (e.g., Golden Malrin, Fly-Die), which combine 1% methomyl with a molasses/pheromone attractant that is highly palatable to dogs. Dogs readily consume large quantities — a tablespoon of bait granules can deliver a lethal dose to a medium-sized dog (estimated minimum lethal dose in dogs 20–40 mg/kg). Onset of toxicosis is rapid (15–30 minutes post-ingestion): profuse salivation, vomiting, diarrhea, muscle tremors, seizures, bradycardia, respiratory distress, collapse. Fatality rates without immediate veterinary treatment are high. ASPCA APCC designates methomyl fly bait as a top-10 most dangerous pesticide product for dogs. Treatment: emergency emesis if very recent ingestion and not yet symptomatic; intensive symptomatic and supportive care; atropine titration. Irreversible without prompt intervention.

Cats are similarly susceptible to methomyl toxicosis as dogs, though cats are less likely to directly consume fly bait granules due to food preference selectivity. However, outdoor cats in agricultural or rural settings may ingest fly bait or be exposed to agricultural methomyl applications. Indoor cats may be exposed if fly bait products are used within the household. Clinical presentation mirrors the dog context: cholinergic crisis with salivation, vomiting, tremors, bradycardia, and seizures. Cats' reduced capacity for glucuronidation may slow elimination of methomyl metabolites. Immediate veterinary treatment is essential. Subclinical exposure (small bait quantity ingestion) may still cause significant toxicosis in cats due to their smaller body weight.