Antifreeze Poisoning in Dogs

Pug on pavement.

Melissa Lomax Speelman/Getty Images

Many dog owners know that antifreeze is poisonous to dogs, but not all people understand how dangerous antifreeze poisoning can really be. Unfortunately, exposure to even a small amount of toxic antifreeze can quickly lead to death. Antifreeze poisoning in dogs is a very serious matter.

Antifreeze is a common hazard during winter, but dogs can easily be exposed to it any time of year. Dogs are most likely to be poisoned if they ingest it, but it technically can be absorbed through the skin). It is believed that dogs are attracted to antifreeze because it has a sweet taste. A dog may find antifreeze in storage areas but is not uncommon to find small puddles of it in driveways, garages, and roadways. Be wary of puddles that have a greenish color or iridescent haze. Avoid letting your dog lick the ground, especially where there are puddles.

Some types of antifreeze are more toxic than others. Most brands contain the active ingredient ethylene glycol, which is the most toxic kind. Antifreeze with the active ingredient propylene glycol or methanol is still poisonous, but not as serious as an antifreeze with ethylene glycol.

It takes very little ethylene glycol to poison a dog. The average toxic dose depends on the dog's size.

Toxic Doses of Ethylene Glycol in Dogs

(amounts are approximate)

 Dog's weight (lbs)  Toxic Dose (tbsp)
10                1-2
20                2-3
40                5
60                8
80                10-11

The Merck Veterinary Manual states: "The minimum lethal dose of undiluted EG is 1.4 mL/kg body wt in cats, 4.4 mL/kg in dogs, 7–8 mL/kg in poultry, and 2–10 mL/kg in cattle. Younger animals may be more susceptible."

Signs of Ethylene Glycol Poisoning

After exposure to ethylene glycol, most dogs begin showing signs very quickly. At first, it may look like alcohol intoxication. For the first 30 minutes to 12 hours after exposure, dogs often exhibit the following signs: 

  • Vomiting (due to GI irritation)
  • Lethargy
  • Drunkenness, ataxia, trouble walking
  • Increased thirst and/or urination
  • Excessive salivation
  • Sedation or stupor

These initial signs usually subside after the first 12 hours. Unfortunately, this can make you think that the dog is improving. However, the toxin continues to do serious damage to the internal organs. 

Somewhere between 36 and 72 hours after intoxication, the dog's kidneys will begin to fail. At this point, the dog will once again show signs of illness:

If aggressive veterinary treatment has not begun before this final stage, the chances of survival are significantly decreased.

What To Do If Your Dog Gets Into Antifreeze

Unfortunately, ethylene glycol poisoning often leads to death. The sooner it can be detected and treated, the better the chance of recovery. If you suspect your dog has been exposed to antifreeze, contact your veterinarian immediately. The best thing you can do is to head straight to the nearest open veterinarian. If it's after hours, find an emergency clinic near you.

DO NOT induce vomiting unless your vet instructs you to do so. Also, don't just wait for your dog to show improvement. Without treatment, dogs who have been poisoned by antifreeze will almost certainly suffer kidney failure followed by death. Time is of the essence in order to prevent death.

How Vets Diagnose Antifreeze Poisoning

If you think your dog has been exposed to antifreeze, but you're not sure, talk to your veterinarian about all the facts you know. The vet will look at your dog's history, physical examination, and laboratory data together to make a diagnosis.

If you know for sure your dog was exposed to antifreeze, your vet will still need to run several tests. At the very least, the vet will perform blood work to assess organ function and cell counts. A urinalysis will also be done to look for abnormalities (such as calcium oxalate crystals, which are often seen after ethylene glycol poisoning).

Once the vet can determine the extent of damage done so far and the state of the dog, a treatment plan will be developed.

Treatment for Antifreeze Poisoning in Dogs

If ethylene glycol poisoning is detected early enough (within 8-12 hours of exposure), the first goal of treatment is to prevent further metabolism of the ethylene glycol. This is done by administering either the drug fomepizole (also known as 4-MP) or ethanol (also known as ethyl alcohol, which is drinking alcohol).

Because 4-MP is very expensive, not all vets will have it on hand. Therefore, ethanol is commonly used in the form of grain alcohol or even vodka. It is important to know that alcohol is normally toxic to pets. However, when given carefully and properly by a vet to treat antifreeze poisoning, it interferes with the absorption of ethylene glycol. Never attempt to treat your dog with ethanol alcohol on your own--it can cause more harm and even lead to death.

The next step in treatment involves intensive supportive care. IV fluids are administered to keep the dog hydrated and correct electrolyte imbalances. Medications are given to ease symptoms. The dog's vitals are closely monitored and lab work is checked often in order to measure recovery.

Unfortunately, not all dogs will survive ethylene glycol poisoning, even with aggressive treatment. The sooner you can get the affected dog to the vet, the better chance there is of survival. Do not delay if there's a chance your dog was exposed to antifreeze!

Protecting Your Dog From Antifreeze

The best thing you can do is to protect your dog from exposure to ethylene glycol. In addition to antifreeze, this chemical can be found in brake fluid, de-icers, certain cleaners and other household or automotive solutions.

  • Store all chemicals out of reach of your dog and clean up any spills immediately.
  • Consider changing to a less toxic form of antifreeze (one that contains propylene glycol or methanol).
  • Use caution when walking with your dog. Keep your dog from stepping in or drinking from puddles with unknown liquids.
  • Never let your dog roam free because you never know what he may be exposed to.

Antifreeze is deadly, but your dog does not have to suffer from this dreadful toxicity if you are careful in and around your home.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.