Antifreeze Toxicosis: Do You Know How Deadly This Winter Threat Is?

Medical articles
Antifreeze Toxicosis in Pets

Many pet parents are aware that antifreeze is toxic to their dogs and cats, yet The Humane Society Legislative Fund estimates that at least 10,000 - 90,000 animals are victims of this toxicity every year. Why? Many animals, including our dogs and cats, will voluntarily drink ethylene glycol if antifreeze is spilled or leaks onto garage floors or driveways.

Just How Much is Toxic?

Antifreeze is extremely toxic, causing kidney failure that is often fatal in just a few days. A cat that walks through spilled antifreeze and licks its paws may ingest enough to be fatal. As little as 2.5 tablespoons of antifreeze can kill a 20-pound dog.

What Causes the Toxicosis?

Most antifreeze solutions contain high levels of ethylene glycol, an ingredient that is extremely poisonous to dogs and cats. Ethylene glycol affects the brain, liver, and kidneys. Death can occur less than a day after ingestion. For this reason, antifreeze ingestion is a medical emergency. If you suspect your pet has consumed antifreeze, contact a veterinarian immediately!

Symptoms Of Antifreeze Toxicosis

The progression of antifreeze toxicosis is a horrible thing to witness in pets and occurs in two main phases. Signs that may be seen within 30 minutes of toxin ingestion include:

  • Lethargy

  • Drooling

  • Vomiting (may be bright green like antifreeze)

  • Incoordination or acting drunk

  • Excessive urination

  • Excessive thirst

  • Muscle twitching

The second phase of symptoms may begin in as little as 12 to 36 hours:

  • Rapid breathing

  • Seizures

  • Little or no urination as the kidneys shut down

  • Coma and death

Prevent Antifreeze Toxicosis

Use antifreeze containing propylene glycol, which is less toxic than ethylene glycol. It is more costly than ethylene glycol based antifreeze, but this is a small price to pay.


If your suspect your pet consumed antifreeze, contact your veterinarian immediately. If your pet receives veterinary care within an hour of ingestion, the veterinarian may be able to induce vomiting and flush out the contents of the stomach. Your veterinarian can safely administer antidotes to the ethylene glycol to prevent the poison from being further metabolized. Your pet may be kept at the hospital to monitor for kidney function.

Once kidney failure has begun, it may be difficult to save the animal because the damage from ethylene glycol is often irreversible.

Is a Bittering Agent a Solution?

You may have previously heard the good news that a bittering agent would soon be added to antifreeze. In 2012, The Humane Society Legislative Fund and Consumer Specialty Products Association jointly worked to make it a requirement for manufactures of engine coolant products in all 50 states and the District of Columbia to add a bittering agent, denatonium benzoate. In this quest, they were successful.

Denatonium benzoate has been used in common household products for years and as an anti-biting ingredient for products in both pets and people. It gives the products it is added to a bitter flavor and decreases the sweetness in the hope of attracting less pets and children to consume toxic products.

While this is excellent, and many states have this now in effect, if you are the pet parent of a dog and have tried traditional “no chew” products, you may be aware that they very frequently do not deter chewing or biting.

In addition, while many states have currently rolled out this legislation, some states have deadlines for manufacturers of engine coolant products into 2015.

While it is hopeful this will decrease the number of victims that suffer from antifreeze toxicosis, this is not a perfect solution and vigilant care must still be taken to avoid this deadly toxin.