Antifreeze poisoning is a fairly common toxicity seen in veterinary medicine. It is often the agent used by the truly evil people who intentionally poison other people’s pets, but it is also a common household product that pets may accidentally come in contact with. The problematic chemical in antifreeze is ethylene glycol. It has been said that it tastes good to pets so they will drink it voluntarily, but in at least one study cats who were deprived of water refused to drink antifreeze voluntarily even when they were extremely thirsty. Of course all bets are off when guessing what a dog would voluntarily ingest. I have treated dogs who have eaten bags of ice melt and fertilizer, so lapping up antifreeze isn’t much of a stretch for the species.
Antifreeze that goes into the car is the most common source of ethylene glycol in the household, but another less obvious source can be exterior paints for the house. Anyone who has tried painting with the assistance of pet supervision knows that the assistance consists mostly of tracking through the paint pan or otherwise spilling and wearing paint in any way possible. The act of licking exterior paint off saturated feet can give a significant dose of ethylene glycol that could be fatal to a smaller animal
One tablespoon of 50/50 radiator antifreeze/water mix is enough to be fatal to a cat, and ½ cup of the same mixture is enough to be fatal to a 20 pound dog.
Very often the ingestion of antifreeze is not witnessed. If you happen to be lucky enough to know that your pet has just consumed ethylene glycol you have a precious window of opportunity to have a veterinarian induce vomiting and treat with activated charcoal to get as much of the toxin as possible out of the body before it can be absorbed. There are some other medications that can further counteract the poisoning and increase the chances of survival if started before the animal becomes sick. Sadly, without the use of psychic powers, we often only discover the situation after it is too late to help.
About 1-3 hours after ingesting ethylene glycol a pet will often act drunk. The body first metabolizes the ethylene glycol into a substance that acts much like alcohol on the brain. After a few hours the intoxication passes and the animal acts normal again. Beneath the surface however, the body chemistry is anything but normal. The metabolic products created as a result of ethylene glycol breakdown cause severe derangements in many systems, but they most prominently cause the kidneys to stop functioning. This sudden kidney failure causes vomiting, diarrhea, extreme lethargy, seizures and collapse that appears 24-96 hours after exposure. By the time these symptoms are present the damage has already been done and is usually too severe to save the animal.
Of course the best way to safeguard pets from antifreeze poisoning is to keep all household sources contained and secured, keep drips from vehicles cleaned up, and don’t allow pets access to places where they may come in contact with antifreeze. And for those who intentionally poison pets with ethylene glycol, I invite you to come and have a cocktail or two with me. I have a special mix for you that I bet you are just going to love.