Can Dogs Eat Onions?

Julia Henriques
Can Dogs Eat Onions

With all of the fruits and veggies that are great for dogs, you may wonder if dogs can eat onions. Is it dangerous to share your burgers, soups, or tacos with your dog?

Are Onions Really Toxic To Dogs?

Yes, onions are toxic to dogs. And all parts of the onion are toxic. It’s surprising because people eat onions all the time. Why can people eat onions with no issues but onions are dangerous for dogs?

Here’s why. Onions contain N-propyl disulfide. Relatively harmless to humans, this compound can lead to the breakdown of red blood cells in dogs. This breakdown can cause hemolytic anemia  … also called Heinz body anemia.

Hemolytic anemia tricks your dog’s immune system into thinking red blood cells are invaders. The immune system attacks these “invaders” and destroys red blood cells. This affects your dog’s red blood cells’ ability to transport oxygen. Severe hemolytic anemia can be life-threatening, so you need to keep your dog away from onions! 

Other Foods In The Onion Family

Onions are in the allium family of plants. And most other allium vegetables are also toxic for dogs. Garlic is the exception and is very good for dogs in moderate amounts (more about garlic later). The allium family of veggies includes:

  • Garlic
  • Onions 
  • Leeks 
  • Chives
  • Scallions 
  • Shallots

As well as fresh onions, you should also avoid giving your dog foods with onion products like onion powders and dehydrated onions. Onion powder is in everything from soup to baby food. Read ingredient labels carefully when you buy prepared foods. These onion products aren’t as potent as raw onions but in large enough quantities, they could cause your dog harm. 

One research study shows that some manufacturers may add powdered onion to their canned dog food so always read ingredients very carefully, even with food made for dogs!

Even if you don’t intend to feed your dog onions, he may get into the garbage, compost or vegetable garden, so you need to know. 

How Much Onion Is Toxic To Dogs?

Onions can be toxic if your dog eats approximately 0.5% of his weight. For bigger dogs, this might seem like a lot but for a smaller dog, it doesn’t take much. For example, ¾ of a cup of onions is enough to make a 75 lb dog sick. ¼ of a cup can cause onion toxicity in a 25 lb dog. Lastly, for a 10 lbs dog, 1½ tablespoons is enough to do damage. 

If You Know Your Dog Ate Onions

If you realize that your dog has wolfed down some onions, you should speak to your vet right away about what to do. 

Depending on when your dog ate the onions, the approach will differ. If your dog has just eaten the onions, your vet may recommend you induce vomiting to try and get the onion out of his system. Sometimes you can induce vomiting at home using hydrogen peroxide. Other times your vet may prefer to use emetic drugs that cause vomiting. Your vet may also suggest giving your dog activated charcoal.

Holistic veterinarian Patricia Jordan DVM recommends you always have TOXIBAN activated charcoal in your first-aid kit. But you can also buy activated charcoal in capsules from a health store. Activated charcoal can help absorb toxins from the gastrointestinal tract. But this will only work within a short time after your dog eats the onions. Once they’re fully digested, it’s too late. 

Symptoms Of Onion Toxicity

Your dog may get into onions without you realizing it … so you need to know how the signs of onion toxicity. Symptoms may even occur days after he ate the onions. Symptoms like these can be cause for alarm: 

  • Decreased appetite
  • Weakness
  • Lethargy
  • Fainting
  • Pale gums
  • Diarrhea
  • Problems with balance and movement
  • Elevated heart rate
  • Discolored urine

You may not know if your dog has eaten onions. But if he starts showing any of these symptoms, they could be a sign of severe illness, so contact your veterinarian right away. 

How Veterinarians Treat Onion Toxicity

In more serious cases when anemia has begun, your vet will likely give your dog IV fluids. She will also look to treat any liver damage that may have occurred. A blood transfusion may be necessary for very serious cases. Sometimes your dog may need supplemental oxygen. 

Even when you take your dog home, you will have to monitor him for additional anemia symptoms. 

Note: You might have to take your dog to a conventional veterinarian for this treatment. But keep in touch with your holistic vet. She’ll be able to help you once your dog gets home, using more natural remedies to support his recovery. 

Is Garlic Toxic To Dogs?

When you read about foods that are toxic to dogs, you’ll almost always see garlic on the list. While they’re part of the same family, garlic is not toxic to dogs … in fact, garlic is very healthy for dogs, when you give fresh, raw garlic in the right amount for your dog’s size.

A lot of the confusion comes from one study. Dogs were fed 5 grams of garlic per kilo per day. This did cause an adverse effect but it was also an absurd amount of garlic. To get a similar result you’d have to feed 4 full heads of garlic (approximately 60 cloves) to a 75 lb dog or 23 grams of garlic (6 to 8 cloves) to a 10 lb dog. 

In moderate amounts, garlic can be good for your dog’s health. It can help with:

  • Expanding blood vessels … can lower blood pressure.
  • Preventing blood clots.
  • Stimulating the lymphatic system to remove waste.

Garlic also has antibiotic, antifungal, and antiparasitic properties. And it’s useful in repelling ticks and fleas

That’s not to say you shouldn’t use some caution. Don’t give garlic to puppies under 6 months and use caution with pregnant dogs. It’s best to ask your holistic vet before giving a pregnant dog garlic. 

RELATED: Learn more about the health benefits of garlic for dogs …

The Final Word

A small piece of onion shouldn’t hurt your dog but it doesn’t take much to put your dog in peril. If your dog steals your leftovers or gets into garbage or compost with contain onions, talk to your vet right away and watch for symptoms of onion toxicity.

The sooner you can treat it, the sooner your dog will be back to his healthy self.


Harvey JW, Rackear D. Experimental Onion-Induced Hemolytic Anemia in DogsSage Journals. 1985, July 1.

Kovalkovičová N, Šutiaková I, Pistl J, Šutiak V. Some food toxic for petsInterdiscip Toxicol. 2009 Sep: 169-76. 

Beynen AC. Onion in canned dog food. ResearchGate. May 2020.

Lee KW, Yamato O, Tajima M, Kuraoka M, Omae S, Maede Y. Hematologic changes associated with the appearance of eccentrocytes after intragastric administration of garlic extract to dogsAmerican Journal of Veterinary Research. 2000 Nov;61(11):1446-50.

Houston DM, Myers SL. A review of Heinz-body anemia in the dog induced by toxins. Vet Hum Toxicol. 1993 Apr;35(2):158-61. PMID: 8470361.

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© 2024, Four Leaf Rover - The content on this website is not meant to replace veterinary advice. Please support the hard working holistic vets who make this information possible. To find a holistic or homeopathic vet near you or to find one who will do phone consultations, visit The Academy Of Veterinary Homeopathy.