Can dogs eat onions?

Updated 24/04/2024

Onions form the base of so many of our meals - from sauces to stews, dips and soups, they're in just about every meal we humans tuck into. And with snouts twitching by your side as you cook up a storm in the kitchen, we wouldn't be surprised if you've found yourself wondering - can dogs eat onions? Or are onions poisonous to dogs? Unfortunately for your pup with an all-too curious palette, onions are highly toxic to dogs, and should never be fed to our furry friends. To find out why onions are such bad news for our canine companions, take a look below as we dig into questions from pet parents on the topic.

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Are onions poisonous to dogs?

So can dogs eat onions at all? Or are all onions simply bad news for our furry friends? Unfortunately, onions are highly poisonous to dogs, along with the rest of the allium family. Eating onions can cause a variety of seriously unpleasant symptoms for your pup, so be sure to keep your stash well out of paw’s reach.

And if you’re wondering - can dogs eat cooked onions - while we can see the logic, unfortunately adding heat to onions doesn’t make them any less toxic to dogs. So, don’t consider handing down any table-side titbits, no matter how cute those puppy dog eyes might be.

How much onion is toxic to dogs?

The size of your pup along with various other health factors affects how much onion will cause the nasty symptoms of toxicity. And while there are many offering figures on this, the best thing to do is to be super vigilant when it comes to onions and dogs - even the smallest amount could cause your pup to experience symptoms. And, if you think your pooch might have nibbled on something containing onion (or any other allium for that matter), contact your vet immediately.

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Why are onions bad for dogs?

So, just why are onions so dangerous to dogs? Well onions and other alliums contain a compound called N-propyl disulphide which causes a breakdown of red blood cells and therefore anemia in dogs. How does this work, then? Well as the compound attaches onto the oxygen molecules into your pup's red blood cells, which causes oxidative damage. This means that the body is then less effective at carrying oxygen around the body, and actually fools the body into thinking that the red blood cells are invaders. Because of this, the body then destroys its own red blood cells, which results in hemolytic anemia. This is of course seriously dangerous for our furry friends, and the more onion that's eaten, the worse the anemia is likely to be.

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What to do if your dog eats onions

So we've settled the question - can dogs eat onions - but what should you do if you come home to your dog nibbling on an onion, or you find out they've somehow managed to steal a few morsels of an onion-based meatloaf? Well you can't be too cautious when it comes to dogs and onions. So, as a matter of emergency, we suggest you call your vet immediately. The sooner your pup gets medical treatment, the less severe their symptoms of toxicity will be, so don't wait to act.

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Symptoms of onion poisoning in dogs

So we can all agree that dogs and onions simply aren't a match, but what are the signs the poisonous allium has got to work? Well we'll list the symptoms of onion poisoning in dogs below, but don't wait for them to arise before contacting your vet.

• Lethargy
• Pale gums
• Reduced appetite
• Weakness
• Red tinge to urine
• Collapse
• Vomiting
• Diarrhea
• Increased heart rate
• Panting 

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Other alliums and onion products

So now we've cleared up the question - can dogs have onions - what about other alliums and onion products? Let's take a look.

Can dogs have green onions?

While green onions might look, smell and taste different to regular onions, green onions are highly toxic to dogs, and should never be shared with our furry friends, even in small quantities.

Can dogs have onion powder?

Along with fresh onions, onion powder is also harmful to dogs, so don't consider letting your pup have a try of something, even if it's just a dusting of onion powder used.

Can dogs eat garlic?

Dogs can't eat garlic under any circumstances - it contains compounds N-propyl disulfides and thiosulfate, which cause damage to and destroys the body's red blood cells.

Can dogs have leeks?

As a member of the allium family, leeks are strictly off-limits to our furry friends. Like onions and garlic, they also contain compounds that damage the red blood cells and eventually cause anemia.

Can dogs eat chives?

While chives might add a fragrant aroma to many of our dishes, they're highly toxic to dogs and should never be shared, even in small amounts.

So, the jury is certainly in on the question - can dogs eat onions - onions and all other alliums are highly toxic to dogs, so be sure to keep them well out of paw's reach. And if you've got an abundance of those gorgeous (yet deadly) purple-sprouting giant alliums in your back garden, make sure you keep your curious pup's snout well away. 

Meet our veterinary expert, Holly

This article has been checked by veterinarian Holly Anne Hills BVM BVS BVMedSci. After graduating from the University of Nottingham, Holly spent two years working as a farm animal vet. She then spent some time traveling and volunteering in India, working at neutering clinics and with injured street dogs. Holly now works in small animal practice, and balances this with writing, volunteering with the comms team at Vet Sustain, and she is also a marine mammal medic!

Other foods that are not safe for dogs

So we've settled your query - can dogs have onions - but what other foods can't dogs eat? Take a look below to get started.

• Walnuts
• Nutmeg
• Pumpkin spice