Antifreeze Toxicity

Ethylene Glycol (EG) toxicity is one of the major concerns of the cold season. Ethylene Glycol is the active ingredient in most antifreeze-type liquids such as radiator coolant, windshield de-icer, brake fluid, etc. It is unfortunately very sweet, which is what often attracts animals to ingest it. The fatal “dose” is quite low, recorded at as low as a ½ tsp per pound, and much lower in cats. It is rapidly absorbed by the GI tract, so treatment should be sought ASAP. It can easily be fatal, especially if left untreated.

Signs and Symptoms

  • Ataxia (“drunken stagger”)
  • Sedated appearance
  • Lethargy
  • Excessive thirst
  • Excessive urination
  • Vomiting
  • Panting

In extreme cases, we can also see coma and death.


There are two ways, aside from physically seeing your pet ingest it, to diagnose EG toxicity. There is a veterinary available blood test kit. The trick with this test is that you want to have it completed ASAP after the ingestion. The half-life of EG in the blood is about 3 hours, so if you don’t have the test done within 1-6 hours of ingestion, you can receive a “false negative”. Basic kidney bloodwork is also helpful to have, and specific crystals can often be seen in the urine.


The antidote to EG toxicity is fomepizole and must be given within 8-12 hours from ingestion. IV fluids are also helpful to support the kidneys and help flush the toxins out. Depending on the animals presentation different medications may be needed.

If you suspect your animal may have ingested antifreeze, head to your closest emergency clinic immediately.

Written by Aurora Animal Clinic