Less than a tablespoon of antifreeze can kill a cat or dog

Antifreeze poisoning is one of the most common poisonings for both cats and dogs. Antifreeze’s relatively pleasant taste (please don’t try this at home) and the extremely small dose needed to be toxic accounts for its frequent occurrence. Ethylene glycol, antifreeze’s main component, is lethal to both cats and dogs.

Car coolant level sign
Car coolant drops regularly? Even less than a tablespoon of antifreeze can kill a cat.

Exposure to ethylene glycol most commonly occurs when a car radiator leaks and the pet licks up the spilled chemical. Ethylene glycol is also used in some house heating and cooling systems and to prevent freezing of toilets. An additional risk is poor storage of the chemical.

Ethylene glycol has an extremely small lethal dose:

  • For cats: 1.4 milliliters per kilogram of body weight (0.021 ounces per pound)
  • For dogs: 4.4 milliliters per kilogram of body weight (0.067 ounces per pound)
  • Note: antifreeze usually contains from 20-60 percent by volume of ethylene glycol

For example, a lethal dose for a cat weighing 4 kilograms (8.8 pounds) is only 11.2 milliliters (0.42 ounces) of antifreeze containing 50% of ethylene glycol. Do your math: 11.2 milliliters is less than a tablespoon.

Signs of antifreeze poisoning in cats and dogs

IMPORTANT: Your pet has a very good chance of recovery IF AND ONLY IF treatment is started within a few hours after ingestion (3 hours for cats, 5-8 hours for dogs). If your dog or cat shows any of the signs mentioned below, an emergency vet visit is required.

In the early stages, during the first 24 hours after ingestion, ethylene glycol affects a pet’s central nervous system, gastrointestinal system, and urinary system.

Early signs of antifreeze poisoning are:

  • nausea and vomiting
  • loss of coordination
  • head tremors
  • increased urination
  • depression
  • increased thirst (dogs only)

Twelve to 24 hours after ingestion, dogs can show significant “improvement”; however, this is misleading. In reality, the antifreeze is now fully metabolized, but renal failure signs have not yet appeared.

Later signs of antifreeze poisoning:

  • loss of appetite
  • salivation
  • vomiting
  • seizures
  • lethargy
  • swollen kidney(s)
  • coma

These signs usually develop after 12-24 hours for cats and 24-48 hours for dogs, when ethylene glycol has affected the pet’s kidneys.

Diagnosis of antifreeze poisoning in dogs and cats

Whenever your cat or dog shows any of the above signs of antifreeze poisoning, or if you suspect (yes, even if you just suspect) that your pet has ingested antifreeze, you should take your pet to an emergency veterinarian immediately.

Confirmation of ethylene glycol poisoning is based on the signs shown and how sure the owner is about the pet’s ingestion of antifreeze or other ethylene glycol-containing substances.

Laboratory tests, such as blood and urine tests may be helpful to confirm the diagnosis. However, unless the vet clinic has its own lab, these tests are rarely done because of the very small window for taking action.

Treatment of antifreeze poisoning in dogs and cats

If you respond early (within 1-2 hours after ingestion), induced vomiting may be helpful to prevent further metabolization of ethylene glycol. You can read how to induce vomiting in dogs and cats here.

In the early stages, a vet will administer medication to slow down the metabolization of ethylene glycol. DO NOT DO THIS AT HOME! This medication usually contains a substance which “competes” with the ethylene glycol, thus reducing the amount of ethylene glycol metabolized.

Since the cat or dog will be losing a lot of water, fluids will also be administered to counter the risk of dehydration.

As already mentioned, early intervention will increase the likelihood of recovery for dogs and cats. If, however, you let too much time pass, the chances of recovery drop sharply.

How to prevent antifreeze poisoning in pets

When using products that contain ethylene glycol, precautions must be taken to prevent pet and human poisoning:

  • Regularly check your cars for any spills and check the antifreeze level.
  • Clean up any leakage. Cover the spill with sand, cat litter, or other absorbent material, let it soak up the antifreeze, and then dispose of the mixture.
  • Store antifreeze in its original container and in a place out of reach of pets and children.
  • Properly dispose of used antifreeze. Ask your car repair service how to do this.
  • Whenever you use ethylene glycol-containing substances, keep pets out of the area.

Remember that preventing your cat or dog from ever coming near antifreeze is a much better strategy than taking him to vet’s office for ethylene glycol poisoning treatment.