For Engines Only – The Dangers of Antifreeze in Pets

Antifreeze is used in vehicle engines and is often stored around sheds and garages. It commonly contains an ingredient, ethylene glycol, which can be deadly to your pets by causing severe kidney damage. Affected pets will initially appear drunk and nauseous, which progresses to continuous vomiting, seizures, coma, and death as the kidneys fail within 1-3 days of ingestion. To ensure that your pet has the best chance of survival, veterinary attention must be sought immediately after you suspect an exposure.

Antifreeze is an integral part of your engine’s coolant, or radiator fluid, and is essential to keeping the engine running smoothly during extreme temperature fluctuations. The most common active ingredient in antifreeze for vehicles is ethylene glycol, a sweet, odorless, and colorless liquid with a molecular structure similar to ethanol (alcohol). Since our pets typically find this sweet liquid delicious, they won’t easily get deterred from drinking enough to cause harm. Certain companies do add a bitter tasting deterrent to antifreeze products, which may minimize exposure, but unfortunately, does not prevent an ingestion. Ethylene glycol is extremely dangerous when ingested and can lead to kidney failure and death if not addressed right away.

Shortly after ingestion, ethylene glycol acts very similarly to ethanol by causing neurologic changes in our pets. Once it makes its way to the liver, it is metabolized into a few different toxic compounds that are responsible for many of the life-threatening symptoms that follow.

The first signs you may notice in early stages of ethylene glycol ingestion include vomiting, unsteady gait (ataxia), increased thirst and urination, and possibly seizures. These signs usually begin within 30 minutes of ingestion but can be delayed up to 12 hours. During this time, calcium oxalate crystals are also starting to form, even though they may not be seen in the urine immediately. The following signs include a rapid heart rate and faster breathing, which occur up to 24 hours after ingestion. Anywhere within 24-72 hours after ingestion, kidney failure will begin to set in, which can be as early as 3 hours in cats. The pet will have a decreased urine output, depression, continuous vomiting, and eventual seizures, coma, and death if untreated.

To provide your pet with the best chance at a full recovery, treatment must be initiated as soon as possible. As your pet’s kidney injury progresses, the risk of permanent damage or failure beyond repair increases. If lethal doses of ethylene glycol are ingested, it is fatal without veterinary treatment. Even small volumes can be deadly, especially for cats. Antidotes are available but may not be in stock at all veterinary practices and need to be given within a few hours of exposure to be effective. Several diagnostic tests may also be performed to confirm if an exposure occurred.

Help reduce the risk of ethylene glycol toxicity to pets by limiting their access to garages, sheds, and other places where vehicle supplies are kept and take extra care to keep antifreeze and other products containing ethylene glycol stored out of reach. Be sure to check for and clean up any spills after adding antifreeze to your vehicle. If you believe that your pet has accidentally ingested antifreeze, immediately seek veterinary attention or call Pet Poison Helpline at 1-800-213-6680. Having the product packaging on hand can be extremely helpful in determining the amount of ethylene glycol ingested and guiding treatment recommendations.


Written by:

Cecelia Harmon, Pet Poison Helpline DVM student extern, Virgina Tech class of 2023

Kathy Mackenzie, CVT, Training Coordinator & Veterinary Information Specialist II, Pet Poison Helpline