Is antifreeze toxic to dogs?
Yes, and it is one of the most dangerous poisonings a dog can have. Antifreeze contains ethylene glycol, which tastes sweet, so dogs drink it willingly, and the body turns it into compounds that destroy the kidneys within two to three days. An antidote exists, but it works best in the first few hours and not at all once the kidneys fail. Go to a vet now, even if your dog seems normal or seems to recover.
General information, not veterinary advice. If your pet may have eaten this, contact a vet now; do not wait for signs.
What to do right now
- Go to the nearest vet or emergency clinic now; call ahead so they can prepare
- Take the container, or a photo of its label, with you
- Estimate the earliest time your dog could have drunk it
- Do not make your dog sick or wait to see if signs appear
Go to an emergency clinic now if
- You saw or suspect your dog drank or licked antifreeze or coolant
- Your dog licked a puddle under a car, in a garage or on a driveway
- Your dog seems drunk: wobbly, falling over, confused or sleepy
- Your dog is vomiting, drinking and urinating more, or has stopped urinating
- Your dog has a seizure or collapses
Who to call
Your own vet first. If they are closed, the nearest emergency or out-of-hours clinic.
In the United States
Both answer 24 hours a day and may charge a consultation fee.
Signs to watch for
| Sign | Usually starts |
|---|---|
| Wobbly, drunk-looking walk, confusion | 30 minutes to 12 hours |
| Vomiting, increased thirst and urination | 30 minutes to 12 hours |
| Apparent recovery (kidneys still being damaged) | Around 12 hours |
| Little or no urine, painful belly | 36-72 hours |
| Vomiting, mouth ulcers, drooling, no appetite | 36-72 hours |
| Seizures, coma | 36-72 hours |
Why is antifreeze toxic to dogs?
Ethylene glycol is the main ingredient of most car antifreeze and coolant. On its own it acts like alcohol, but the liver converts it into acids and crystals that damage the kidneys. The Merck Veterinary Manual describes severe acid build-up in the blood and injury to the kidney tubules, leading to kidney failure 36 to 72 hours after drinking.
It is so dangerous because the amount needed is small, the taste is sweet, and the most damaging phase happens after the early signs have faded. VCA Animal Hospitals says the prognosis is very poor once signs of kidney damage appear.
How much antifreeze is dangerous for a dog?
A very small amount. The Merck Veterinary Manual gives a minimum lethal dose of 4.4 to 6.6 mL of undiluted ethylene glycol per kg of body weight. For a 10 kg dog, that is 44 to 66 mL, roughly three to four tablespoons. Ready-mixed coolant is usually about half ethylene glycol, so roughly twice that volume of mixed coolant carries the same risk.
Because you can rarely know how much was swallowed, Pativo treats any possible exposure as an emergency. Sources include:
- concentrated antifreeze, which Merck says can be up to 95% ethylene glycol
- ready-mixed coolant and leaks under cars
- some brake and transmission fluids
- heat-exchange fluid in some solar panels and ice-rink equipment
Since 2012, manufacturers in the US have added a bittering agent, but Merck notes some animals still drink it. Do not rely on the taste to protect your dog.
What will the vet do?
Speed is everything. The antidote works by stopping the liver from converting ethylene glycol into its toxic products, so it only helps while unconverted ethylene glycol is still in the body. Once the kidneys are failing, Merck says blocking that conversion is of little benefit because almost all of it has already been processed.
The vet will run a blood test for ethylene glycol if the clinic has one, check blood chemistry and urine for crystals, and start the antidote quickly if exposure is likely. Activated charcoal is not expected to help much. Treatment continues in hospital with intravenous fluids and close monitoring of kidney function and acid levels. Dogs already in kidney failure may need dialysis, available only at some referral centres.
Merck's summary is direct: the outlook gets worse the longer treatment is delayed, and is guarded to poor once urine output drops.
How do I stop it happening again?
- Store antifreeze and coolant in their original, sealed containers on a high shelf or in a locked cabinet.
- Clean up spills and drips immediately with absorbent material, then rinse the area.
- Check under parked cars for leaks, and keep dogs out of garages and driveways while topping up.
- Dispose of old coolant through a garage or recycling centre, never down a drain or on the ground.
- Consider propylene glycol antifreeze, which Merck describes as less toxic and less attractive to animals, though not harmless.
Cats are at risk too, and kidney failure develops faster in them: see antifreeze in cats. Pativo's emergency floor always rates antifreeze as "go now".
Questions owners ask
My dog seemed drunk and now looks better. Is it over?
No. Merck describes a brief apparent recovery around 12 hours after drinking antifreeze, while the kidneys are still being damaged. Go to a vet now.
How much antifreeze can kill a dog?
The Merck Veterinary Manual gives a minimum lethal dose of 4.4 to 6.6 mL of undiluted ethylene glycol per kg. For a 10 kg dog that is less than half a cup of concentrate, and some products are over 90% ethylene glycol.
Is pet-safe or propylene glycol antifreeze harmless?
Merck describes propylene glycol antifreeze as less toxic than ethylene glycol, with a better outlook, but it is still not harmless. Check the label and call your vet with it.
Sources
- Merck Veterinary Manual: Ethylene Glycol Toxicosis in Animals
- Merck Veterinary Manual, owner edition: Ethylene Glycol (Antifreeze) Poisoning
- VCA Animal Hospitals: Ethylene Glycol Poisoning in Dogs
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