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Can Dogs Eat Onions? Vet-Reviewed Toxicity & Safety Tips

Written by: Jackie Brown

Last Updated on April 15, 2024 by Dogster Team

red onions on rustic wood

Can Dogs Eat Onions? Vet-Reviewed Toxicity & Safety Tips


Dr. Lauren Demos  Photo


Dr. Lauren Demos

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Dogs are often indiscriminate about what they eat, so we have to be careful with what types of snacks and table scraps we feed them, as they may contain ingredients that are harmful to dogs. One common food to avoid feeding to dogs is onions. All forms of onions, including onion powder, are toxic to dogs.

Onions can make dogs really sick and are extremely detrimental to their health. Here’s what you need to know about onions and what to do if your dog accidentally eats some.

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Why Can’t Dogs Eat Onions?

All types of onions, including red, yellow, and white onions, are toxic to dogs. Onions contain n-propyl disulfide, an oxidant that’s toxic to dogs. When n-propyl disulfide is ingested, it damages the red cells and results in hemolysis. Simply put, hemolysis refers to when red blood cells are broken down and destroyed. N-propyl disulfide isn’t affected when heated, so both raw and cooked onions are unsafe for dogs.

A sick, older dog lying on the floor.
Image Credit: stonena7, Thinkstock.

What About Onion Powder?

All forms and parts of an onion contain n-propyl disulfide. So, dogs shouldn’t ingest the bulb, flower, or leaves. They also can’t eat foods incorporated with minced or juiced onions. Foods seasoned with onion powder are harmful to dogs as well.

Since onions are commonly found in many dishes, broths, and snacks, it’s extremely important to check ingredient lists before feeding something to your dog. Many popular savory snacks contain onion powder, and meat dishes, like meatballs and meatloaf, often contain onions.

What Happens When Dogs Eat Onions?

The effects that onions have on dogs will depend on how much is eaten. Onion poisoning typically occurs when a dog eats more than 0.5% of their own body weight in onions. The following amounts of onions are considered to be toxic levels for dogs:

Dog Weight Raw Onion Diced Onions Onion Powder
10 pounds 1/10 of a medium-sized onion 1/10 cup 1/3 teaspoon
30 pounds 1/3 of a medium-sized onion 1/3 cup 1 teaspoon
60 pounds 2/3 of a medium-sized onion 2/3 cup 2 teaspoons

Dogs that eat a small amount of onions are likely to experience gastrointestinal upset. They may vomit, have diarrhea, or lose their appetite. If onions are ingested in greater quantities, you may see your dog exhibit the following signs of onion poisoning:

  • Abdominal pain
  • Pale gums
  • Lethargy
  • Unbalanced gait
  • Increased heart rate
  • Red or brown urine

Ingesting a large amount of onions will lead to hemolysis, which can be fatal. It’s also important to note that consistently feeding dogs food with small amounts of onions can still lead to blood cell damage.

What to Do if Your Dog Eats Onions

The effects of onion poisoning will vary, so it’s best to contact your veterinarian or an animal poison control hotline right away if you suspect that your dog has eaten onions. After completing an assessment, your veterinarian may start treatment by inducing vomiting or giving your dog activated charcoal, which can absorb toxins and prevent them from getting absorbed by the gastrointestinal tract. In severe cases, your dog may require IV fluids or a blood transfusion.

Most dogs will make a full recovery from mild cases of ingesting onions if they receive proper treatment. Since onion toxicity can potentially be fatal, it’s important to get your dog to veterinary care as soon as possible.

dog sitting on table against young male veterinarian making prescription notes in document
Image Credit: SeventyFour, Shutterstock

Avoid Allium Vegetables Altogether

Onions belong to the Allium genus. Many other common vegetables belong in this genus, including:

  • Green onions
  • Chives
  • Leeks
  • Garlic
  • Shallots

All Allium plants are toxic to dogs and will cause the same issues as onions. Therefore, dogs shouldn’t eat any of these types of vegetables in any type of form.

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All forms of onions are dangerous to dogs and should never be fed to them. If your dog accidentally eats onions or food containing onions, make sure to contact an animal poison control hotline or your veterinarian right away. You’ll want as much time on your side to help stabilize your dog.

Lastly, if you want to share some food with your dog, you can check the ingredient list to ensure it doesn’t contain any onion products. However, it’s best to stick to snacks and treats that are specifically made for dogs, as this is the best way to prevent your dog from eating any harmful ingredients.

Featured Image Credit: Bukhta Yurii, Shutterstock

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