Antifreeze Poisoning in Dogs: A Race Against the Clock

Antifreeze tastes sweet, kills quickly, and has a middle stage where the dog looks like it is getting better. That stage is the trap.

Antifreeze is the one on this list that frightens vets most, and the reason is not just that it is lethal. It is that it lies to you.

A dog that has drunk coolant goes through a stage, some hours in, where it appears to pick up. The wobbliness passes, it seems brighter, and a worried owner decides to wait until morning. Underneath, the kidneys are being destroyed. By the time the dog is obviously ill again, the antidote has usually run out of road.

So if there is any chance your dog has come into contact with antifreeze, stop and ring a vet now. Not after this paragraph.

What to do

1. Treat it as life-threatening even with no symptoms at all. This is not caution, it is the whole game.
2. Ring immediately. The antidote only works inside a narrow window. In the UK, the Animal PoisonLine. In the US, the Pet Poison Helpline or the ASPCA Animal Poison Control Center.
3. Say what, how much and when, as best you can.

Why so little does so much

The active ingredient is ethylene glycol, and automotive antifreeze is roughly ninety-five per cent of the stuff. Once swallowed, the body breaks it into compounds that wreck the kidneys.

Two things make it unusually dangerous. The first is potency: a very small amount can be fatal, so there is no such thing as a reassuringly small spill. The second is that it is sweet. Dogs and cats will happily lap a puddle of coolant off a garage floor, which is not true of most poisons, and it means exposure often happens without anybody seeing it.

The three stages

Early on, a dog looks drunk. Wobbly, uncoordinated, drooling, often vomiting, drinking and urinating more than usual. Some dogs have a seizure at this point.

Then comes the lull. The dog seems better. This is the stage that costs lives, because it reads as recovery and it is nothing of the sort.

Late, the dog goes off its food, becomes lethargic, vomits, and can progress to seizures and coma as the kidneys fail.

If you take one thing from this page, take the middle stage. Improvement is not evidence that your dog is safe.

Two things not to do

Do not wait for symptoms before ringing. By the time the signs are unmistakable, the window for the antidote may already have shut.

Do not try to make your dog sick unless a vet or poison line tells you to.

Winter, garages and car parks

Coolant leaks onto driveways, garage floors and hotel car parks, and it is most in use exactly when it is coldest. A bright puddle under a parked car in January is worth walking your dog around rather than through.

Windscreen de-icer, some motor oils, brake fluid and even snow globe fluid can contain the same chemical, so it is not only the bottle marked antifreeze.

If you keep any at home, it is worth switching to a propylene glycol product. It does the same job and is far less dangerous if a dog gets into it.

Around the house

Check the garage floor and the driveway where you park, particularly in cold weather when a leaking coolant system is under most strain, and mop up any bright puddle rather than leaving it to dry.

If you keep antifreeze or screenwash, keep it sealed and off the floor, and switch to a propylene glycol product where you can.

Sources

This article was written using guidance from Pet Poison Helpline, a 24/7 animal poison control service for North America; Animal PoisonLine (VPIS), the UK's only 24/7 poison advice line for pet owners, run by the Veterinary Poisons Information Service; and ASPCA Animal Poison Control Center, a leading 24/7 animal poison control resource in the United States. This guidance is for general information and does not replace a consultation with your own veterinarian. In an emergency, always contact a vet. Read [how we write our health guidance](https://rochsociety.com/how-we-write-our-health-guidance/). Last reviewed July 2026.