Antifreeze poisoning--a warning!

Antifreeze poisoning (ethylene glycol poisoning) has historically been one of the most common forms of toxicity seen by veterinarians. In most countries, antifreeze is odourless and has a sweet taste, which can be attractive to curious or thirsty animals and children.  With its sweet taste, pets will consume great quantities of antifreeze before being repulsed by its aftertaste. By then, it is too late, as it does not take a significant amount of its active chemical, ethylene glycol, to cause fatal damage to their system; less than three ounces (or approximately 1/3 cup) of antifreeze is sufficient to poison a medium-sized dog, while a teaspoon is enough to kill a cat.

Antifreeze poisoning typically happens when antifreeze drips from a car’s radiator, where it is licked off the ground and ingested by a pet. Ethylene glycol is also found in engine coolant and hydraulic brake fluids, used in the plumbing systems of cabins and other vacation homes in extreme climates to prevent broken pipes in winter, and occasionally used to weigh down portable basketball hoops. 

Antifreeze poisoning affects the brain, liver, and kidneys. Acute cases of antifreeze toxicity (within 12 hours of ingestion) often present as if the animal was intoxicated with alcohol: stumbling, vomiting and depression are common signs. Seizures, increased urination (initially; in later stages, urinary output is decreased) and increased thirst may also be seen.

The kidneys are the organ most severely affected, and even if the animal seems to improve initially with treatment, they may succumb shortly after exposure to kidney failure (3-5 days post ingestion). The kidneys shut down, and the animal is unable to produce urine.

Success of treatment is dependent upon quick treatment. Therefore, if antifreeze ingestion is known or even suspected in a pet, do not delay. This is not a "wait-and-see" situation; kidney damage will be more severe as time (hours) go by.

When seen at a veterinary hospital immediately after ingestion, a pet will likely be run through a series of detoxification procedures (e.g. gastric lavage or activated charcoal administration).  Regardless of timing post ingestion, they will to need to undergo a series of diagnostic tests including blood work, urinalysis and an abdominal ultrasound (if possible) to assess the appearance of the kidneys. Known antidotes can be administered to dogs (not helpful in cats) to help prevent the damage from ethylene glycol, but these are typically only beneficial 8-36 hours post ingestion. Aggressive fluid therapy via an intravenous line is concurrently administered to flush toxins from the kidneys.

Ethylene glycol intoxication is a scary situation, as survival directly correlates to the amount ingested and time of treatment administration. Prognosis for any animal exhibiting any clinical signs is grave. Even if presented for appropriate veterinary care within 1-2 hours of exposure, prognosis is guarded.

Things that we would like you to remember:

  • Please store all products containing ethylene glycol carefully.
  • Exposure to antifreeze or another product containing ethylene glycol (known or suspected exposure) warrants immediate veterinary emergency assessment.
  • The chances for successful treatment directly correlate to the amount of ethylene glycol ingested and time of treatment administered.

The good news for pets and people is that major manufacturers in the U.S. have come to an agreement in principle to add bitter tasting substances to the products that contain ethylene glycol. As this change takes place, some sources (such as the Humane Society Legislative Fund) estimate that 90,000 pets and children a year  in the U.S. will be spared from painful, often fatal kidney failure.