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The danger of antifreeze

22 January 2017
The danger of antifreeze

Ethylene glycol is the tasty (to cats) but highly toxic component of antifreeze. Spilt antifreeze can be licked off paws, or ingested along with water from puddles. Early symptoms of poisoning include vomiting, drooling and lack of co-ordination, followed by lack of appetite and excessive, or very little, urination. Get the cat to the vet as soon as possible if s/he shows these. Prompt treatment is vital.

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For many household pets, winter weather brings a deadly threat that comes in a plastic bottle. It is ethylene glycol, a chemical commonly used in antifreeze. Antifreeze is said to be sweet and animals like to eat or drink it. But ingestion of antifreeze can often be fatal if it's not immediately treated.  Even a relatively small amount can prove lethal: one teaspoon (1.4ml) is enough to kill a cat.  It also acts very fast - in many cases, your pet can die within 24 hours and if you are not treating it within a few hours of ingestion, there is a serious chance of permanent kidney damage, usually fatal.  Cats Protection reported 1,197 cases of anti-freeze poisoning between November 2012 and December 2014, an average of 50 deaths per month.

How does antifreeze kill cats?

Ethylene glycol is metabolized by the liver and travels in the bloodstream to the kidneys, where it forms insoluble calcium oxalate crystals inside the renal tubules.  Once metabolism of the ethylene glycol has reached a certain point, there is no way to stop it. Because these crystals are insoluble, there is no way to remove them from the body. They cause permanent damage to the kidney tissue, which can ultimately lead to kidney failure.

An animal that has ingested ethylene glycol must receive immediate medical attention. Those caught in the act of drinking the antifreeze have the best chance of survival because medical attention can be administered immediately.

Signs that a cat has antifreeze poisoning

The main signs to look out for in a cat within 30 minutes to 12 hours after ingestion:
• Drooling saliva and looking depressed initially and possibly vomiting;
• They may then appear to recover, but a day later are unwilling to eat (kidneys now have physical crystal damage);
• Any evidence of green fluid (a fluorescent dye is usually added) around the paws/base of tail (use a black light if you have one);
• Seeming wobbly, uncoordinated gait or seeming ‘drunk’;
• Head tremors
• Thirst (kidney damage)

If you suspect a poisoning, see your vet immediately.  The initial signs can last from 1 to 6 hours and death may occur between 3 to 4 days.

Prevention is key

Most antifreeze products that contain ethylene glycol have a fluorescent dye added so they glow under a UV light. If antifreeze poisoning is suspected, a quick and inexpensive way to determine if antifreeze was ingested is to have your veterinarian shine the light on the paws, and under the tail of the animal. If antifreeze residue is present, the hair will glow. Avoid shining the light into the eyes of the animal.

Treatment for ethylene glycol poisoning can be expensive and can require extended hospitalization. In addition, treatment is not always successful if the product has been metabolized. For this reason, prevention is essential.  Regardless of what kind of antifreeze you use, it is important to keep pets out of it. 


• Watch for leaks in your car and keep pets away from the area where antifreeze is stored. 
• Be careful not to spill antifreeze when using it - make sure you clean up carefully if you do.  A cat may walk through it then lick it off their paws.
• If you drain your antifreeze, do not leave it in an open container because animals will be attracted to it. 
• Dispose of this waste properly and keep empty and full antifreeze containers away from dogs, who may be tempted to chew on them. 
• Choose an antifreeze that does not contain ethylene glycol.  (There are newer brands of antifreeze on the market that use propylene glycol instead of ethylene glycol. Propylene glycol is commonly found in such products as lotions, creams, and toothpaste and is not as toxic as ethylene

Even people who do not have pets should follow these rules to avoid accidentally poisoning wild animals and pets belonging to other people.

Ending antifreeze poisoning

The tragedies of antifreeze poisoning can only be avoided by people being more cautious day-to-day , but there of course things companies and politicians can do. For example, Switzerland banned ethylene glycol based coolants in supermarkets and general shops for the public in 1972. Instead, Propylene Glycol is used instead which is far less lethal to pets.

In the UK, there have been online petitions to add a bittering agent (commonly known as Bitrex or Aversion) to ethylene glycol anti-freeze products to make it unpalatable to pets and humans, as well as adding a clear warning on the external packaging.  We hope that the dangers of antifreeze will one day be phased out for good.

See the Huffington Post's recent article on this issue by Andrew Bucher (vet and co-founder of MedicAnimal.com) here