Antifreeze is Poisonous to Dogs and Cats

Author: Dr. Jason Nicholas

Published: December 30, 2014

Updated: May 21, 2021

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antifreeze is poisonous to petsIf you’re like most people, you likely don’t think about the antifreeze in your car very often. And you likely only change it, or have it changed, every few years. But if you’ve got pets (or children, or care about the environment), the antifreeze you and your neighbors have in your cars and garages is actually very important.

Ethylene Glycol – What Every Pet Owner Should Know

Most antifreezes contain ethylene glycol, a chemical compound that causes significant, often fatal, problems for both cats and dogs.

When an unsuspecting pet first licks up the antifreeze — which, sadly, many do —  the ethylene glycol (EG) can cause early signs such as:

  • staggering and loss of balance,
  • increased thirst and urination,
  • and excessive drooling due to the alcohol component of EG.

The more dangerous part of the toxicity though occurs when the liver starts to metabolize the EG into other compounds, which themselves have wide-ranging disastrous effects within the body.

One of the most damaging effects is the formation of mineral crystals which settle in and lead to failure of the kidneys. This is the main cause of death in ethylene glycol antifreeze poisoning cases, and this crystal formation can begin is as little as 12–24 hours for cats and 24–72 hours for dogs.

Later signs of EG poisoning, indicating acute kidney failure, often include:

  • decreased energy and interactions
  • lack of appetite
  • vomiting
  • increased thirst and urinations (initially), followed by decreased thirst and lack of urinations
  • bad breath
  • collapse

Because treatment is more likely to be effective when initiated prior to the formation of these mineral crystals, any pet that has known or suspected exposure to antifreeze should be brought immediately for veterinary evaluation and testing. It takes just a few licks to cause serious damage to a cat (licking it off their paws or their fur can be enough -- they don't need to lick it directly off the ground or from a puddle), and just a few good laps can cause problems for a dog.

UPDATE (Sept. 21, 2015): Further increasing the importance of prevention (and earlier recognition and treatment in cases of exposure) is the fact that the prefered treatment and antidote for ethylene glycol poisoning — a compound called Fomepizole (a.k.a. 4-MP or Antizol-Vet) — has become increasingly more difficult for we vets to get our hands on. A shortage made even more difficult when FDA approval for this drug was pulled in April 2015 at the request of the manufacturer, who has discontinued production of the drug. This shortage means that more cases are now needing to be treated with intravenous grain alcohol (ethanol), an effective treatment, but one that can have more potential complications compared to treatment with Fomepizole.

Precautionary steps to prevent EG Antifreeze toxicity in your pets include:

  • Keep cats indoors and dogs under reliable leash control, do not let your pets roam
  • Store antifreeze (and any other automotive chemicals) behind securely closed cabinet doors or on high shelves
  • Promptly and thoroughly clean up any antifreeze spills
  • Use or request a pet-safer propylene glycol (PG) based alternative (Sierra by Peak, Low-Tox by Prestone, or the PG-based antifreeze by Amsoil) whenever changing or topping off your antifreeze/engine coolant radiator fluid
  • Raise awareness amongst friends & family so they, too, can make pet-safer choices

Note too that antifreeze isn’t used just in cars and trucks. It’s also present in some snow globes and added to toilets in winter cabins in certain parts of the country (to prevent the water from freezing). And, in some places, it’s even added to garden fountains to prevent winter freezing. See how this last application is affecting cats in England.

And speaking of keeping things from freezing...check out our suggestions for pet safer ice melters and how to identify if your pet is suffering from being exposed to those that contain sodium chloride.

About the author

Profile picture for Dr. Jason Nicholas

Dr. Jason Nicholas

Dr. Nicholas graduated with honors from The Royal Veterinary College in London, England and completed his Internship at the Animal Medical Center in New York City. He currently lives in the Pacific Northwest.

Dr. Nicholas spent many years as an emergency and general practice veterinarian obsessed with keeping pets safe and healthy. He is the author of Preventive Vet’s 101 Essential Tips book series.

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