Antifreeze poisoning in dogs and cats
Toxic agent: Ethylene glycol · Reviewed 2026-08-18
Phone a vet now, before reading on. Have ready: your pet's weight, roughly how much was eaten and when, and the packaging if there is any. ASPCA Animal Poison Control (+1 888 426 4435), Pet Poison Helpline, or Animal PoisonLine in the UK.
Antifreeze tastes sweet, a teaspoon can kill a cat, and it has an antidote that only works if it is given within hours. Of everything on this list, this is the one where speed matters most.
What it actually does
Ethylene glycol itself is only mildly intoxicating. The liver converts it, via alcohol dehydrogenase, into glycolic acid and then oxalate. The acid causes severe metabolic acidosis; the oxalate binds calcium and forms crystals that block the kidney tubules. The antidote works by occupying the enzyme so the conversion never happens — which is why it is useless once the metabolites have already formed.
How much matters
The lethal quantities are genuinely small:
| Cats | about 1.5 ml/kg — roughly a teaspoon for an average cat |
|---|---|
| Dogs | about 4.4–6.6 ml/kg |
| Typical coolant | 50–95% ethylene glycol |
| Antidote window | cats about 3 hours, dogs about 8 hours; after that the prognosis collapses |
Some newer coolants use propylene glycol, which is much less toxic. The bottle tells you which, and taking a photograph of the label on the way to the clinic is genuinely useful.
What you will see, and when
Onset: 30 minutes to 12 hours, in three distinct phases. Typical course: Kidney injury declares itself at 12–72 hours.
- 30 min – 12 hoursAppears drunk: wobbling, vomiting, excessive thirst and urination, then apparent recovery
- 12–24 hoursFast breathing and heart rate as acidosis builds — the deceptive middle where the animal looks better
- 24–72 hoursKidney failure: no urine, vomiting, mouth ulcers, seizures
What the vet will do
The antidote is fomepizole, or ethanol where fomepizole is unavailable. Alongside it: intravenous fluids, bicarbonate for acidosis, and monitoring of kidney values and urine output. Dialysis if the kidneys have already failed and it is available.
Outlook
Good if the antidote is given inside the window. Very poor once the animal is in renal failure — this is a poisoning where hours change the outcome completely.
Dogs and cats are not the same here
Cats need far less and have a shorter antidote window. Cats also walk on garage floors and then groom.
Where it comes from in a normal house
- Car coolant and radiator fluid, especially spills and drips on a driveway
- Screen wash and de-icer
- Brake fluid
- Some snow globes and ornamental liquids
- Toilet antifreeze in caravans and holiday homes
The thing people get wrong
“They only licked a bit off the floor.”
A teaspoon is a fatal dose for a cat, and licking a puddle is the classic exposure. Do not wait for symptoms — the treatable window closes before the serious symptoms start.
PawLife keeps your pet's weight, medication and feeding history in one place, so when you make this call you can answer the vet's questions in seconds. The full food safety database is free.
Get PawLife on the App StoreFrequently asked questions
How much Antifreeze is dangerous?
Some newer coolants use propylene glycol, which is much less toxic. The bottle tells you which, and taking a photograph of the label on the way to the clinic is genuinely useful.
How long after exposure to Antifreeze do symptoms start?
30 minutes to 12 hours, in three distinct phases. Appears drunk: wobbling, vomiting, excessive thirst and urination, then apparent recovery. Kidney injury declares itself at 12–72 hours.
Is Antifreeze worse for cats or dogs?
Cats need far less and have a shorter antidote window. Cats also walk on garage floors and then groom.
Is it true that: They only licked a bit off the floor.
A teaspoon is a fatal dose for a cat, and licking a puddle is the classic exposure. Do not wait for symptoms — the treatable window closes before the serious symptoms start.
Related emergencies
Sources
This page is information, not veterinary advice. Toxic doses vary with body weight, age, breed and individual sensitivity, and the figures above exist to explain what a vet is assessing, never to decide that an amount is safe. If you are reading this because something has already been eaten, call a vet.