Antifreeze Poisoning in Dogs & Cats (Ethylene Glycol Poisoning)

During certain times of the year (such as summer and winter), dogs and cats are more exposed to antifreeze. Untreated, antifreeze poisoning can be fatal to pets. Prompt, immediate treatment is necessary in order to save a dog or cat’s life from poisoning.

Sources of antifreeze:

The primary dangerous source of antifreeze is automotive radiator coolant. This is typically a high concentration of ethylene glycol (EG), and come in 95-100% concentrations. Other sources of antifreeze include windshield deicing agents, brake fluid, motor oil, developing solutions for hobby photographers, wood stains, solvents, and paints. Here in Minnesota, a lot of people put antifreeze into their cabin’s toilet to prevent it from freezing during the winter, and we see a lot of toxicities here at Pet Poison Helpline® from dogs running into cabins and drinking out of the toilet. Finally, there are rumors of small amounts of antifreeze in holiday ornaments such as imported snow globes. Recently, some were found to contain antifreeze (ethylene glycol) in the liquid. If a snow globe falls off the table and cracks open, and your dog or cat licks up the contents of the snow globe, there is the risk of antifreeze poisoning.

Mechanism of action:

Ethylene glycol, the primary ingredient in antifreeze, is metabolized by the body to highly poisonous metabolites which lead to severe, acute kidney failure and secondary development of calcium oxalate crystals forming in the kidneys.

Common signs of poisoning:

There are three stages seen with ethylene glycol poisoning:

  • Stage 1: This occurs within 30 minutes to 12 hours, and looks similar to alcohol poisoning. Signs of walking drunk, drooling/hypersalivating, vomiting, seizuring, vomiting, and excessive thirst and urination are seen.
  • Stage 2: This occurs 12-24 hours after a dog or cat has gotten into antifreeze, and signs of “alcohol” poisoning appear to resolve, when underlying severe internal damage is still occurring. Signs of drunkenness seem to improve, but signs of an elevated heart rate, increase breathing effort, and dehydration may start to develop.
  • Stage 3: In cats, this stage occurs 12-24 hours after getting into antifreeze. In dogs, this stage occurs 36-72 hours after getting into antifreeze. During this stage, severe kidney failure is developing secondary to calcium crystals forming in the kidneys. Severe lethargy, coma, depression, vomiting, seizures, drooling, and inappetance may be seen.

Antidote and treatment:

There are only two antidotes for antifreeze poisoning: either ethanol or 4-MP (fomepizole). Cats must be treated within 3 hours of ingesting of antifreeze to be effective, while dogs must be treated within 8-12 hours of ingestion. Delayed treatment often is not effective, and once a dog or cat has developed kidney failure, the prognosis is poor.


As little as one teaspoon of antifreeze when ingested by a cat or a tablespoon or two for a dog (depending on their size), can be fatal. If you think your dog or cat has gotten into antifreeze, it is very important that you seek veterinary care immediately for blood testing for antifreeze poisoning (including an ethylene glycol test and venous blood gas test).