What Does Antifreeze Do to Cats?

Outdoor cats can mistake sweet-tasting antifreeze for a treat.
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When your car's in danger of freezing or overheating, antifreeze is the answer. But when it comes to your cat, antifreeze ingestion is a poison that can be lethal. To understand what antifreeze does to cats, you need to understand what it is and why it's a problem.


What makes antifreeze so toxic to cats? A chemical called ethylene glycol. Cats can easily mistake it for water, and its sweet smell makes it enticing. Worse, the chemical tastes as sweet as it smells, making it more likely poor kitty will ingest it. When your car uses antifreeze, the antifreeze becomes contaminated with potentially hazardous metals, such as lead, zinc, copper, chromium and cadmium. While these obviously pose a risk to your pet, the ethylene glycol is typically the culprit in cases of antifreeze poisoning. The National Oceanic and Atmospheric Administration estimates that as little as a teaspoon can kill a cat.


At first, the poisoned cat may just seem out of sorts -- as if he's disoriented or clumsy. He may start to drool or vomit, and in some cases he'll seem extra thirsty. All that extra water he drinks leads to extra visits to the litter box. This occurs within hours of ingesting the antifreeze. In late stages, fatigue, vomiting, seizures and even coma can occur. The cat will not want to move. Bleeding from the mouth or rectum is possible. By this time, it's too late. The kidneys have likely been damaged beyond repair. The failing kidneys lead to a distinctively putrid smell.


When a cat -- or person, since ethylene glycol is toxic to mammals in general -- drinks antifreeze, his body breaks it down into oxalic acid. When oxalic acid and the calcium in the cat's body combine, it creates crystals that block and damage his kidneys. The kidneys typically filter wastes from the blood, but the oxalic acid is toxic. The result is kidney failure.


It is imperative to take a cat to the veterinarian as soon as you suspect antifreeze poisoning has occurred. There's no time to wait -- treatment with 4-MP or ethanol needs to take place within hours to prevent the poison from damaging the kidneys. Once kidney damage is severe, aggressive fluid therapy or dialysis may help, but in most cases it's simply too late to save the kitty's life.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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