Cold Weather Warning: The Dangers of Antifreeze (Ethylene Glycol)

As we head full steam into the cold weather season, many people are starting to winterize their homes and property. Winter preparations often include adding fresh antifreeze to car radiators. Unfortunately, many people don’t realize the serious dangers antifreeze presents to pets.  

Sadly, the Humane Society estimates that 10,000 animals die annually from highly preventable antifreeze poisoning. To help keep pets safe this season, Newtown Veterinary Specialists issues the following warnings and advice:

Ingestion of antifreeze or Ethylene Glycol (EG) is a true medical emergency as it can result in acute kidney failure and death. Seek immediate veterinary attention if you suspect that your pet has ingested antifreeze!

Five steps to antifreeze poison prevention:

1.       Never leave antifreeze containers open, unattended or in reach of pets. Store it safely out of reach in tightly closed containers. 

2.       Thoroughly clean up all antifreeze spills—even very small ones.

3.       Purchase antifreeze that contains a “bittering” agent that makes the antifreeze less tasty to your pet.  Massachusetts passed a law recently stating that retail antifreeze containers must include a bittering agent.  However, commercial antifreeze is not required to have it. Therefore, if you get your car serviced professionally be aware it may contain the “sweet” EG.

4.       Don’t let your pet roam unattended.  Cats should be kept indoors for maximum security.  Dogs should be leashed or kept in a fenced area.  Even if you don’t have antifreeze on your property, a pet can easily find leaks in parking lots, driveways, farms and near dumps.

5.       If your pets are outdoors, always make sure they have non-frozen water available to drink so they don’t turn to antifreeze instead.


Ethylene Glycol is a clear, odorless water soluble liquid used most typically in antifreeze solution.  It’s also used as an industrial solvent in the manufacture of detergents, paints and lacquers, polishes and other compounds.  Most antifreeze solutions contain upwards of 95% of EG.

Ethylene Glycol is reported to have a pleasantly sweet taste and may have a warming sensation when swallowed.  Pets may ingest it for the flavor, out of curiosity, out of necessity (if water bowls are frozen over) or if they’re intentionally poisoned.

Both dogs and cats are susceptible to poisoning, but cats are more susceptible.  The minimum dose that is lethal in cats is roughly three milliliters per-pound body weight.  For dogs, 10-14 milliliters per-pound body weight may cause death.  Fatality rates for EG intoxication reported by top veterinary schools range from 44–70% for dogs and 78-96% for cats.


Rapid diagnosis of antifreeze poisoning is crucial. Your veterinarian will start with blood and urine analysis.  Certain types of crystals may be seen in the urine and certain blood parameters such as serum osmolality and anion gap will be measured.  However, those specific blood and urine changes are not always seen. There are some commercially available test kits that can measure EG in the blood.  However, EG may no longer be present at 48-72 hours after ingestion.  Because most antifreeze contains a special dye to help find radiator leaks, your veterinarian can examine vomit and urine with a special light as an additional method for screening; however this is not always reliable.

Treatments for treating EG intoxication are aimed at preventing absorption, increased excretion and preventing metabolism of the drug.  The current drug of choice for inhibiting metabolism EG into its dangerous metabolites is fomepizole (4-methylpyrazole). 

If you would like more detailed information about the negative effects EG has on the body, then read on:


Ethylene Glycol is absorbed rapidly from the gastrointestinal (GI) tract and distributed rapidly throughout all body tissues.  Serum levels can starting rising one hour after ingestion and are at their highest three hours after ingestion.  Usually by 48 hours serum levels are undetectable due to metabolism and excretion of the drug.   Unmetabolized EG is excreted by the kidneys into the urine.   The metabolism of EG occurs in the liver.

It was once thought that the unmetabolized form of EG might be toxic to pets.  The unmetabolized form of EG can cause central nervous system depression.  However, it’s now thought that byproducts of metabolism of EG result in most of the toxicity seen.   The metabolic by-products including glycoaldehyde, glycolate, glyoxylate, and oxalate all have slightly different properties that may contribute to toxicity.

Clinical stages

EG intoxication is classically described in three stages.  The signs owners may see can vary and are related to the amount the pet ingested.

Stage 1

The first stage occurs 30 minutes to 12 hours after ingestion and is associated with central nervous system (CNS) signs.  The following symptoms may be noted: “drunken” or wobbly gait, weakness, seizures, muscle twitching, low body temperature, head tremors, abnormal eye movements, coma and death.  Gastrointestinal symptoms such as vomiting may be seen.  Dogs (but not generally cats) will sometimes display excessive thirst.  Both species can be seen to urinate more than normal.

Stage 2

Stage two is characterized by changes to the heart and lungs; this stage is less well recognized in pets than in people.  Some cats may develop an enlarged heart.  Dogs and cats may also develop fluid in the lungs.

Stage 3

Stage three occurs within 24-72 hours of ingestion and is the stage where kidney failure is seen.  You may notice that your pet is not eating, vomiting or seems depressed.  Blood work can show elevations in kidney values.

Newtown Veterinary Specialists advises you to assist in the treatment of your pet by seeking prompt emergency care if you suspect antifreeze ingestion!

Further, you can help even more pets stay safe this winter by warning family members and friends about the serious dangers of antifreeze.

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.


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