Antifreeze poisoning is one of the most common poisonings for both cats and dogs. Antifreeze has a 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. It’s scarily simple, small amounts of antifreeze kills cats and dogs.
In this article you’ll learn how much antifreeze is fatal to your pets, the symptoms of antifreeze poisoning, and what to do if your pet ingests antifreeze.
How much antifreeze is fatal to cats?
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) is fatal.
- For dogs: 4.4 milliliters per kilogram of body weight (0.067 ounces per pound) is fatal.
- Note: antifreeze usually contains from 20-60 percent by volume of ethylene glycol
For example, a fatal 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. This means your average sized cat can be killed by a very small amount of antifreeze: 11.2 milliliters is less than a tablespoon. For a dog, less than a half a teaspoon per pound of bodyweight is toxic. For easy reference, less than a tablespoon can kill the average sized cat and 5 tablespoons can kill a medium sized dog.
What are the symptoms of antifreeze poisoning in pets?
IMPORTANT: Your pet has a very good chance of recovery IF AND ONLY IF treatment is started within a few hours after antifreeze 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.
Ethylene glycol, the main ingredient in antifreeze is converted by your pets liver into toxic components which causes kidney failure. In the early stages, during the first 24 hours after ingestion, ethylene glycol affects your pet’s central nervous system, gastrointestinal system, and urinary system.
Three stages of antifreeze poisoning
Stage 1: Early signs of antifreeze poisoning are:
- nausea and vomiting
- loss of coordination
- head tremors
- increased urination
- increased thirst (dogs only)
Stage 2: Twelve to 24 hours after antifreeze ingestion, dogs can show significant improvement; however, this is misleading. In reality, the antifreeze is now fully metabolized, but renal failure (kidney damage) signs have not yet appeared.
Stage 3: Later signs of antifreeze poisoning:
- loss of appetite
- swollen kidney(s)
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.
What should I do if I suspect my pet has ingested antifreeze?
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.
How is antifreeze poisoning treated in pets?
If you respond early (within 1-2 hours after ingestion), induced vomiting may be helpful to prevent further metabolization of the ethylene glycol. You can read how to induce vomiting in dogs and cats from the American Kennel Club 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. Similar to if your pet ingested rat poison, contacting your veterinarian urgently is required. If, however, you let too much time pass, the chances of recovery drops sharply. This is because the antidote (fomepizole) is only effective if given within 8-12 hours in dogs.
How common is antifreeze poisoning in pets?
During the colder months of the year, antifreeze poisoning increases. This is because antifreeze while the most common source, ethylene glycol is also found in deicing agents like those for your wind sheild, motor oils, brake fluid, some paints and solvents.
During the winter months, many use antifreeze to prevent their plumbing from freezing by pouring it into their toilets. We’ve even had cases where a snow globe (the festive glass orbs with fake snow) which contained ethylene glycol was broken and a cat drank some of the fluid.
How can I prevent my pet from being poisoned by antifreeze?
When using products around the house 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 and antifreeze containers. Ask your car repair or parts store how to do this.
- Whenever you use ethylene glycol containing substances, keep your pets out of the area.
Remember that preventing your cat or dog from ever coming near antifreeze is a much better strategy than rushing them to your veterinarian’s office for urgent ethylene glycol poisoning treatment. We had one patient that had his dogs stay in his garage while they were at work. They kept their dogs in a large dog run fenced area within the garage where they had access to a doggy door to an enclosed dog run area behind the garage. This prevented them from getting near the cars and any potential chemical spills.
If you are a cat owner, keeping them indoors will help reduce the chances of them getting into dangerous chemicals. For tips, please refer to our article on How to turn an outdoor cat into an indoor cat.
You have learned how much antifreeze is fatal to your pets, the symptoms of antifreeze poisoning, and what to do if your pet ingests antifreeze. You’ve also learned that an “ounce of prevention is better than a pound of cure” in this case. So keeping your pets far away from any chemicals than may contain ethylene glycol. This will go a long way towards a long and happy life with your pet. And keeping your Pet Happy is what we all want.