Antifreeze Poisoning in Cats

6 min read


Ethylene Glycol Poisoning in Cats

Ethylene glycol toxicity is a potentially fatal condition that results from the ingestion of substances containing ethylene glycol, an organic compound commonly seen in antifreeze. (In addition to being found in the car's engines to prevent freezing and overheating, it is used in hydraulic brake fluids.) Cats usually come into contact with antifreeze when it leaks from a car's engine onto the ground, when it is spilled onto the ground while being added to a car's engine, or when the container is left uncapped.

Antifreeze is recognizable by its bright green coloring and "sweet" taste. Although it leaves a repulsive aftertaste, by then it may be too late. Even small amounts can be fatally toxic to the body's organs, including the brain, kidneys and liver.

This is one of the most common forms of poisoning; any breed or age is susceptible. Etylene glycol poisoning is also covered in our emergency section, which includes immediate care that you can give to your cat and tips on prevention. This does not take the place of veterinary care, but will assist you in treating your cat in a timely manner.

Symptoms and Types

Early signs are seen from 30 minutes to 12 hours after ingestion:

  • Nausea and vomiting
  • Mild to severe depression
  • Wobbly, uncoordinated or drunken-appearing gait (ataxia) or movement and knuckling
  • Twitching muscles
  • Short, rapid movements of the eyeball
  • Head tremors
  • Decreased withdrawal reflexes and righting ability
  • Increased urination and increased thirst (polyuria and polydipsia)

Other symptoms often develop 12 to 24 hours after ingestion of ethylene glycol (antifreeze):

  • Symptoms are dependent on the amount of ethylene glycol (antifreeze) ingested
  • Symptoms are almost always sudden (acute)
  • Signs caused by ethylene glycol itself and its toxic metabolites are frequently fatal (metabolites - substances produced by the body's chemical processes as it breaks down the ethylene glycol)
  • Cats usually remain markedly depressed
  • Cats typically do not exhibit increased thirst; producing only small amounts of urine; lack of production of urine is seen 72 to 96 hours after ingestion of ethylene glycol if left untreated
  • May note severely low body temperature
  • Severe sluggishness (lethargy) or coma
  • Seizures
  • Lack of appetite (anorexia)
  • Vomiting
  • Oral ulcers/sores on mouth
  • Salivation or drooling
  • Kidneys are often swollen and painful, particularly in cats


Toxicity is directly related to ingestion of ethylene glycol, the principal component (95 percent) of most antifreeze solutions.


It’s extremely important that you have your cat seen by a veterinarian as quickly as possible after ingestion of anything that contains ethylene glycol. Even if you only suspect that your cat has ingested ethylene glycol, if the cat is showing any or all of the effects of ethylene glycol toxicity, and the substance is accessible in any way (particularly for cats that are allowed to go outdoors unattended), you should take your cat to be checked. If your cat is vomiting or has diarrhea, you should collect a sample of the vomit or fecal contents to present to your veterinarian. Diagnosis may be that much faster, saving valuable time and possibly preventing full organ shutdown if supportive therapy is given quickly.

You will need to provide your veterinarian with a medical background and as much detail of the onset of symptoms as possible. Standard tests include a urinalysis and complete blood test, which will be sent for laboratory analysis immediately. Your veterinarian may also use ultrasound to look at the liver and kidneys, which are often swollen in response to ethylene glycol ingestion.

Ultrasonography can also be helpful. Possible findings may be renal cortices (the external layers of the kidneys) that are hyperechoic as a result of crystals. That is, the external layers of the kidney respond to the sonographic sound waves with a denser echo than the surrounding areas because of the more solid nature of the crystal formation in the renal tissue.

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