Why is antifreeze a danger to your pet?

What is antifreeze and why is it dangerous

The antifreeze additive is a type of alcohol called ethylene glycol, from the same family as the ethanol found in beer, wine and spirits, though with a slightly different chemical formula. In its primary form it is not dangerous (you can safely touch it) but if swallowed and absorbed into blood, it gets transformed by the liver into substances that are very toxic for the kidneys, but also the heart and the brain. One of these byproducts also forms sharp microcrystals in the kidneys, adding to the damage.

Ethylene glycol is colourless and odourless, but its sweet taste makes it appealing to dogs who are likely to lick it off the ground or containers. Cats may accidentally lick spills too (they can't taste sweet), but usually end up ingesting it when cleaning it off their coat and paws.

The extent of the toxic effects depends on how much of it the pet has had and how long ago. Sadly, as little as one teaspoon of it can be fatal to a cat or small dog and one or two tablespoons can cause serious damage to a larger dog.

What to do if your pet had antifreeze

If you saw your dog or cat lick some of it, do not try to make them vomit at home, but take them straight to your vet immediately.

Have someone call the vet practice for you to tell them you are on your way so they can prepare for your arrival, but do not waste time on the phone making an appointment yourself, this is a true medical emergency and time is of essence.

How to recognise a possible antifreeze poisoning in your pet

If you have not seen your dog or cat swallowing it, but your dog has been around cars or antifreeze unsupervised or your cat roams outdoors and then they start acting strangely, keep in mind that it could be antifreeze poisoning. What you are likely to see depends how long ago they had it.

During the first stage, between 30 minutes to 12 hours after ingestion, you may see the following symptoms in your pet:

• acting ‘drunk’ - moving uncoordinatedly and being disoriented or dull/sedated,

• having muscle tremors,

• drooling and/or vomiting,

• drinking and peeing excessively,

• having a slower heart rate (though admittedly this is a subtle sign to notice),

• having seizures.

In the second stage, 12 to 24 hours after ingestion, you are likely to see:

• breathing rapidly or panting;

• having an elevated heart rate;

• having a dry mouth;

• urinating at lower than normal levels (definitely lower than the previous 24 h).

The last symptom could be mistaken for improvement, but unfortunately it indicates exactly the opposite - the lower urine production happens because the damage to the kidneys approaches its peak and they are simply not working as they should anymore.

The third stage, 24 hours after the ingestion, is marked by symptoms linked to the organ damage in the kidneys, the brain and the heart. In this late stage pets usually show:

• panting and having a bad breath,

• not wanting to eat (or even drink) at all,

• drooling and vomiting,

• a more or less pronounced lethargy,

• frequent seizures or a continuous coma.

Without treatment or if the kidney damage was too extensive, death will follow the coma.

What is your vet likely to do - diagnosis, treatment and prognosis

If the ingestion is fairly certain and happened less than a few hours before seeing the vet, they will make your pet vomit to get rid of any antifreeze still left in the stomach and not absorbed into the bloodstream yet.

The next thing your vet is likely to do is to take blood samples to assess what is the state of the kidneys. These will be repeated several times throughout the treatment to measure kidney function.

There are specific tests that can be done to check if there is any antifreeze or its byproducts in your pet’s blood, but they are not widely available in general practice. So if you haven’t seen your pet having the antifreeze, the vet will make a diagnosis based on the possibility of your pet’s exposure to ethylene glycol and the kidney function indicators on the blood tests.

After this they will start intravenous fluid therapy to support the kidneys in their blood filtering function and add to the perfusion a substance that slows down or blocks the transformation of ethylene glycol into its toxic byproducts, either ethanol or something called 4-methylpyrazole.

The highest concentration of ethylene glycol byproducts in blood is achieved approximately 2-3 hours after swallowing it, so getting your pet diagnosed and treated before that improves the prognosis considerably.

Because of the severe toxicity of antifreeze, the prognosis is guarded in all cases. It usually becomes clear in the next 24 (max 48) hours if the poisoning was mild enough for the kidneys to recover from the injury or not.

Therefore it is best to handle the product carefully, clear any spills immediately and dispose responsibly of leftovers.

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