Can Dogs Eat Onions – An Expert Guide

While the strong flavour and overwhelming aroma of onions makes them massively popular in dishes worldwide, they’re not exactly the most simple or neutral of foodstuffs to deal with.

While many dog owners are looking to supplement their pets’ diets with some extra fruit and vegetables, this is one option to avoid.

Indeed, to those wondering, can dogs eat onions? – the answer is no. Perhaps surprisingly, onions come with plenty of risks to your dog – read on to find out not only what those are, but how to avoid them.

Are onions good for dogs?

Absolutely not – while they’re not as immediately dangerous to dogs as other fruits and vegetables, like grapes or avocados, can be, onions are toxic to dogs.

This is often surprising to dog owners, not only because onions appear so frequently in our own meals – whose leftovers we might want to share with our pooch – but because onions do us next to no harm whatsoever.

Sure, they can be a bit eye watering to peel, and certainly stark enough in flavour to not want to eat them alone – to say nothing of how unappealing their flaky outer peel can be.

But in the case of your dog, he or she will find every part of an onion toxic, including the leaves and stem as much as the skin and the crisp, layered flesh of the onion itself.

The toxic compound in dogs is particularly nasty, and in particularly striking cases, or in cases in which a very young or a very old dog has eaten an onion, it can prove altogether fatal.

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It’s very important to monitor what your dog eats as a result of this, especially if your pet is particularly good at getting scraps from visitors or otherwise getting at his or her human masters’ meals and pantry supplies.

Remember, this counts not only for onions, but also for related vegetables, including garlic, and also chives, shallots and leeks.

For the sake of your dog’s safety, these are all to be entirely avoided – even derived products, such as onion powder.

Even larger dogs will stand to suffer if they eat as much as an entire onion, so keep a close eye on your pet if they’re nosy on what you’ve brought home from your grocery shopping.

Make sure to also scrutinise the ingredients of other things you’re contemplating giving your pet, especially prepackaged foods. Onions are put into far more of our own meals than you might otherwise realise.

While other foods we can give our dogs, like potatoes, lose much of their toxicity potential after cooking them, there is unfortunately nothing to be done about onion toxicity for dogs.

Whether raw or cooked, and no matter how meticulously they’re prepared, onions simply aren’t good for the animal in your life in any way.

Dangers of onions for dogs

The toxic elements in onions cover every part of the plant and the vegetable itself, and that means there is no safe part of this foodstuff that your dog is able to eat.

The toxic reaction dogs get from onions is especially nasty, because it attacks their bloodstream directly – more specifically, their red blood cells.

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It takes but a small amount of onion or onion related products to induce these very risky health issues in your pet.

Many experts agree that as little as 100 grams of onion are all that’s necessary to trigger an untoward reaction in your dog, ultimately leading to bouts of anemia.

If your dog suddenly comes across as weak, uninterested in eating or drinking, passing water with a reddish tint or even scarier symptoms like passing out or lacking in the energy to stand, seek the help of a qualified veterinarian professional immediately.

Anaemia in dogs is a horrible event for them to endure, and in some cases can prove tragically fatal.

It may be possible, if your dog exhibits these symptoms, that he or she has eaten an onion, some garlic, or even seemingly harmless related vegetables like shallots or chive pieces without your knowledge.

While remaining calm, take the relevant steps to make sure your pet comes through this problem in one piece.

What happens when your dog eats an onion

Onions at least have some natural warning signs to animals that they’re not to be messed with, such as their strong odour and overwhelming flavour, especially if eaten alone.

Nonetheless, it’s the toxins within them that you and your dog ought to really watch out for.

The toxins of an onion harm your dog because they trigger an anemic reaction in their bloodstream.

The toxin rather rapidly damages the red blood cells inside your pet, ultimately breaking them down altogether.

This is what’s called oxidative damage, and happens because the molecules of the toxin compound latch onto the red blood cells in the way that oxygen molecules are supposed to instead.

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As the situation for your dog continues to deteriorate, the animal’s body is confused into attacking itself in a strange way.

That’s because, thanks to the foreign attachments to your dog’s own red blood cells, the body breaks them down under the mistaken belief that they are invading substances instead.

A long and scary story short, anemia ensues, which makes your dog weak, lethargic, prone to vomiting or passing out, and even in stark danger of losing their lives altogether if you don’t react fast.

Remember, this is just as much a risk if your dog eats products related to onion, such as onion powders put into some foods, or even prepackaged products like onion rings.

No matter how well the onion is diluted or disguised in a given meal, it still poses quite the danger to your pet, and you should be cautious indeed with what you feed your beloved furry friend because of that.

What to do if your dog eats an onion

Any responsible dog owner will tell you that it’s often troubling enough just keeping track of where your dog can or can’t go, and what food he or she has access to because of that.

As your knowledge of what dogs can eat expands, it can perhaps be even more stressful as you learn just how many foods you need to keep your beloved animal away from for their own benefit.

Perhaps onions are often kept in a cupboard in the kitchen your dog has learned how to open or sneak things out of.

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Maybe you live in a rural area where your dog could slip his or her collar, scamper into a farmyard field and tuck into some onions there – or maybe you’ve a young pup who hasn’t yet learned why he or she need to stop digging through the garbage.

Any way you look at it, it’s daunting to know what to do if your dog eats an onion, or what to do if your dog eats some garlic too.

The anemic reaction is likely to take hold within a few hours, so time is very much of the essence if you’ve just caught your dog eating onions.

If your dog has only eaten a scrap or two of onion – maybe a little sliver of one dropped from a hot dog at a garden party and he or she gulped it off the grass before anyone could stop them – then keep a close eye on your pet.

Remember, just 100 grams of onion is all it takes to do your dog some serious harm, but a tiny accident might not be so severe.

It’s more if your dog has eaten an entire onion, or more, that you really need to ensure you get them to the vet as soon as you can.

This can prove challenging, as your dog is going to feel progressively more weak, poorly and disinclined to follow your advice as their malady takes hold.

Remain calm and make sure that your pet doesn’t panic. Report the emergency to your vet, and await their help accordingly.

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Have water by your dog to keep them well hydrated, and to refresh him or her if they are sick as part of their feeling bad.

If you catch this immediately, your vet may be able to induce vomiting in your dog, expelling the onions before they can enter his or her system and do severe harm.

In other cases, your vet will offer the supplements and care needed to help your pet replenish a healthier bloodstream, and you’ll be able to breathe a big sigh of relief.


Onions are fantastically versatile, so it’s no wonder that their strong flavour makes them a popular addition to so very many of our meals – all over the world.

Yet your dog won’t have such a happy time of it if they eat an onion, and neither can dogs eat garlic, shallots, leeks or chives.

It’s important to ensure your dog can’t accidentally access onions, onion related vegetables or products that have onion extract or onion powder inside.

The risk of illness, anemia and even fatality is far too great to put your beloved dog at risk.

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