Metaldehyde (slug and snail bait) in Pets

Slug pellets containing metaldehyde cause tremors, seizures and overheating in dogs. Convert grams of 2–4% bait to mg/kg and compare with Merck's LD50 of 210–600 mg/kg.

What It Is

Metaldehyde is the active ingredient in many slug and snail pellets. It breaks down in the stomach to compounds that cause severe muscle tremors, seizures and a dangerously high body temperature. Poisoning is sometimes called 'shake and bake' because of these signs.

Where Pets Come Across It

Blue or green pellets scattered in gardens and allotments, opened boxes in sheds, and baits mixed with bran or molasses, which dogs find tasty. Some products also contain a carbamate insecticide.

Which Animals Are Affected

Dogs most often, cats occasionally. Livestock, horses and birds can be poisoned.

Published Toxic Dose

The Merck Veterinary Manual reports oral LD50 values of 210–600 mg/kg in dogs and 207 mg/kg in cats. Residential baits in the US contain 2–4% metaldehyde (20–40 mg per gram) and commercial baits up to 7%. Signs occur well below the LD50, and Merck does not give a minimum toxic dose, so the calculator does not grade the dose.

Signs and How Soon They Appear

Signs usually start within 1 to 3 hours: anxiety, panting, drooling, wobbliness, muscle tremors and twitching, then continuous seizures and a body temperature that can exceed 42 °C. Merck notes that animals surviving the first 24 hours have a good prognosis.

What to Do Right Now

Go to a vet immediately with the product box; this is a true emergency. Keep your pet cool and quiet on the way, but do not try to make it vomit, because a pet that starts seizing can inhale vomit.

Frequently Asked Questions

Sources and References

• Merck Veterinary Manual: Metaldehyde Poisoning in Animals
• Pet Poison Helpline: Metaldehyde

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