The Canine Ledger

Rat Bait and Slug Bait

If your dog ate rat or slug bait, phone a vet now, even if they seem fine. Why the packet matters, why some poisons take days, and what 'pet friendly' hides.

Written by thecanineledger

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If your dog has eaten, or may have eaten, rat or mouse bait or slug or snail pellets: phone your vet or an animal poison helpline now, even if your dog seems completely well. Bring the packet, or a photo of the label showing the active ingredient. Don’t try to make your dog sick unless a vet tells you to. Go now if your dog is trembling, twitching, unsteady, having a seizure, bleeding, or struggling to breathe.

A dog who eats the most common kind of rat poison usually looks fine for days. According to the Merck Veterinary Manual, signs of bleeding typically appear “3–7 days after ingestion of a toxic dose” (Merck, Anticoagulant Rodenticide Poisoning in Animals).

That delay is what makes it dangerous. By the time a dog is visibly unwell, the window when the poison could have been removed from the stomach has long passed.

While rat and slug baits are some of the most common poisonings in dogs, and many dogs treated promptly recover, the outcome depends on two things owners control: phoning early, and knowing what was in the packet. This page explains why.

→ Emergency Signs in Dogs: When to Go Now, Not Tomorrow

1. Why the packet matters

“Rat poison” is not one poison. Different active ingredients act in completely different ways, at different speeds, and need different treatment. Some have an antidote and some don’t.

The baits can look alike, and the brand name doesn’t tell your vet the ingredient. The active ingredient on the label does. If you can’t find the packet, tell your vet who put the bait down (you, a neighbour, a pest-control company), because they may know.

Our note: That baits with different ingredients can look alike is our point, not from a source we read. Don’t assume you know which poison it was.

2. The main kinds of rat and mouse bait

These are the three Merck describes in most detail. All three chapters were written by a board-certified veterinary toxicologist and updated between November 2025 and February 2026.

TypeWhat it doesWhen signs appearAntidote?
Anticoagulants (the most familiar kind)Stops the blood clottingBleeding “typically noted 3–7 days after ingestion”Yes
BromethalinSwelling of the brainNeurological signs “within 1–7 days after exposure”No. “No antidote exists for bromethalin poisoning.”
Cholecalciferol (vitamin D3)Raises blood calcium and damages the kidneysSigns “often develop within 12–48 hours after ingestion”No. “No antidote for cholecalciferol poisoning is available.”

Anticoagulants. Signs of bleeding can be obvious (nosebleeds, blood in urine or stool) or hidden. Merck lists weakness, tiredness, loss of appetite and breathing difficulty, because bleeding can happen inside the chest. It also warns that “Sudden death, though rare, is also possible.” The antidote is given by mouth as a course that lasts weeks. Your vet will usually recheck a blood clotting test after the course ends.

Bromethalin. In the US, Merck says it “quickly became the most common rodenticide exposure in companion animals” after the Environmental Protection Agency’s risk-reduction measures came into force. With no antidote, “The key to successful treatment of bromethalin poisoning is early and aggressive decontamination.”

Cholecalciferol. Because the poison lasts so long in the body, Merck notes that recovery “can take weeks of consistent monitoring and adjustments to treatment.”

Eating a poisoned rodent. Merck lists “relay toxicosis from ingestion of prey or scavenged carrion” among the ways pets are poisoned by anticoagulants. If your dog catches or eats a rat or mouse that may have been poisoned, phone your vet.

Our note: Which rodenticides are sold to the public differs by country. Read the label.

3. Slug and snail bait: metaldehyde

Metaldehyde is “the active component in over 80% of slug and snail baits globally” (Merck, Metaldehyde Poisoning in Animals, reviewed May 2026).

It is fast. In dogs, neurological signs “develop 30 minutes to 6 hours after ingestion.” Merck lists severe muscle tremors, anxiety, unsteadiness, a racing heart, and very high body temperature. Seizures and drooling are common.

It can kill quickly, but prompt treatment works. Merck warns that death “can occur soon after exposure (within 4–24 hours”. But “Animals that survive the first 24 hours of intoxication have a good prognosis”, and “rapid treatment during the first 24 hours can allow a full recovery in most patients within 2–3 days.” There is no antidote.

Banned outdoors in Great Britain. The UK government announced that outdoor use of metaldehyde would be banned in Great Britain from the end of March 2022, to protect wildlife (Defra and HSE press release, 18 September 2020). Old stock can still turn up in sheds and garages. The press release says garden products “should not be disposed of at home”. It recommends local authority waste facilities.

Elsewhere, Merck notes that “Some countries, such as the UK, have banned outdoor use of metaldehyde slug pellets.” It remains in use in other countries.

4. “Pet friendly” slug pellets

Many slug pellets now use iron compounds instead of metaldehyde, and some are labelled as safer for pets. That doesn’t mean they are harmless.

A 2025 study described 61 dogs treated at Australian hospitals after eating iron EDTA, 60 of them from slug and snail bait. “Notably, 20 out of 61 dogs (32.8%) had no clinical signs before presentation.” Vomiting, lethargy, diarrhoea and weakness were the most common signs. Most dogs survived to discharge (91.8%), but severe liver and heart damage did occur (Luswanto et al., Frontiers in Veterinary Science 2025).

The authors suggest that high exposures “could be due to the misleading “pet friendly” labeling on the iron EDTA snail pellets packaging, resulting in owners not keeping them away from pets.”

Our note: We found no study on whether other iron-based slug baits, such as iron phosphate, are a similar risk.

5. What to do

  1. Phone now. Your vet, an emergency clinic, or an animal poison helpline. Don’t wait for signs.
  2. Have the packet, or a photo of the label. The active ingredient, its strength and how much is missing are what the vet needs.
  3. Don’t make your dog sick at home. Your vet may do this at the clinic, if it is still useful.
  4. Go now if your dog is trembling, twitching, unsteady, having a seizure, bleeding, very weak, or breathing hard.
  5. Follow up. With anticoagulants, a dog can seem fine for days. Keep any recheck your vet books.

Our note: Don’t make your dog vomit at home. Our separate page explains why.

→ My Dog Ate Something: Why You Shouldn’t Make Them Vomit Without a Vet · → Animal Poison Helplines by Country: Numbers, Fees, and What Works From Where

6. What we could not verify

Commonly saidWhat we found
“My dog seems fine, so it can’t have been much”Not safe. Anticoagulant bleeding typically appears 3–7 days later.
“All rat poisons have an antidote”No. Merck says there is no antidote for bromethalin or cholecalciferol.
“Pet-friendly slug pellets are safe”Not shown. 61 dogs needed hospital care after eating iron EDTA bait in one Australian study.
“Slug pellets are banned now”Only for outdoor use in Great Britain, from the end of March 2022. Metaldehyde is still used elsewhere.
“A dog can’t be poisoned by eating a poisoned rat”It can. Merck lists eating poisoned prey as one route of anticoagulant poisoning.

Sources

Always confirm with your vet before acting on anything on this page.