Antifreeze Poisoning in Cats

Updated Sep. 12, 2023

Ethylene glycol is an odorless, sweet-tasting, organic chemical that’s found in antifreeze, and it’s poisonous to cats. It’s used in many products to help prevent liquids from freezing at cold temperatures or to aid in temperature regulation for air conditioning systems.

Because of ethylene glycol’s varied uses, it is found in many home and industrial items such as antifreeze, windshield washer fluids, de-icers, solvents, and condenser fluids. The wide variety of uses for ethylene glycol leads to exposure to cats in automobile work/storage areas and air conditioning units, where the chemicals may leak or spill out.

Less than ½ tablespoon of antifreeze can be lethal for your feline. Here are the symptoms of antifreeze poisoning to watch for and what to do if you think your cat got into antifreeze. 

Symptoms of Antifreeze Poisoning in Cats

The guidelines below will give you an idea of what you could see at each stage, depending on how much time has passed since exposure to this lethal chemical.

Stage 1: 30 minutes to 12 hours after exposure (acute signs of toxicity)

This is the most important time to seek veterinary treatment. For the antidotes to be effective and prevent permanent damage, treatment must be initiated in the first 4 hours.

  • Clinical Symptoms: vomiting, lethargy, incoordination, increased urination, seizures, and coma
  • Pets may act like they are “drunk” at this stage of toxicity.

Stage 2: 12-24 hours after exposure (false recovery)

This phase of the toxicity does not always occur.

  • Clinical Symptoms: dehydration, depression, low body temperature
  • Initial clinical symptoms and pet’s outward appearance will improve, but internally, toxic effects are still occurring.

Stage 3: 12-24 hours after exposure (kidney failure)

Typically, if your pet reaches this stage of toxicity, the prognosis for recovery is poor. 

  • Clinical Symptoms: lethargy/depression, vomiting, seizures, not eating, kidney failure, and death
  • At this stage the kidneys have severe damage, so the body is no longer able to filter the blood and produce urine.

What to Do if Your Cat Drinks Antifreeze

Due to the small amount of toxin required and the severity of toxicity with antifreeze, you need to get your cat to a vet immediately if you suspect that they drank antifreeze.

How Do Vets Test for Antifreeze Poisoning in Cats?

There is a test that detects antifreeze by testing for the lethal amount of ethylene glycol in the cat’s blood, but it must be run within 10-14 hours of exposure. Not all animal hospitals have access to this test, so treatment may be based on exposure, exam findings, and standard bloodwork.

Standard bloodwork and urine tests detect changes in the blood that occur well after exposure and toxic effects have occurred. This test will find blood gas changes, elevated kidney values, poorly concentrated urine, and crystals in your cat’s urine, but typically, these results are not observed until at least 3 hours after consumption of ethylene glycol.  

How Is Antifreeze Poisoning in Cats Treated?

Initial treatment for a cat’s exposure is based on how long it’s been since ingestion. If it’s only been 1-2 hours and your pet is not yet displaying symptoms, the vet will induce vomiting or perform stomach lavage (pumping the stomach) to remove the toxin from your pet’s stomach. Stomach lavage must be done under anesthesia. A tube is run from the mouth to the stomach to flush the stomach with water in hopes of removing any toxin that may be in the stomach.

Following this initial treatment, your cat will be placed on IV fluids to help flush their system of toxins. The best treatment, which must be started within 4 hours of exposure, is initiation of antidote treatment with 4-methylpyrazole (4-MP, fomepizole) or ethanol.

The goal of antidote treatment is to prevent the body from absorbing and converting ethylene glycol into its toxic forms in the body. The ultimate goal is to promote its excretion from the body without causing kidney damage. The antidote requires multiple treatments to be effective.

Pets typically are hospitalized for 1-4 days, depending on the severity of illness and damage noted. The prognosis varies greatly depending on when treatment is initiated. Sadly, once cats have developed signs of kidney damage, the prognosis is poor.

How to Prevent Antifreeze Poisoning in Cats

The best way to protect your feline friends from exposure to ethylene glycol is to keep them indoors, which will keep their exposure minimal. Keep all chemicals safely secured and stored. If you notice a spill of any chemicals or leakage from a vehicle, find something to absorb the spilt liquid and clean the area well with water and soap.

Featured Image: iStock/Mr.Chiawchan Thaikrathoke

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Sean Jones, DVM


Sean Jones was born and raised in Louisiana and attended Louisiana State University for veterinary school. He spent most of his career...

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