Can Dogs Eat Onions?

Key takeaway

Onions are incredibly toxic to dogs, and dogs should never consume any part of an onion because it contains a toxic sulfuric compound that causes severe anemia. When left untreated, onion toxicity can lead to organ failure and death.

Many people add onions to their favorite foods, including everything from sandwiches to soups. However, if you love sharing food with your dog, you might ask, "Can dogs eat onions?" The short answer is no. As many pet parents know, there are safe and unsafe foods for dogs. While there are some foods you shouldn't share with your dog because they're simply not healthy for them, there are some you shouldn't share because they're toxic. 

Are onions bad for dogs? Yes. Dogs should never consume any part of an onion because they're toxic to dogs. Onion toxicity is a fairly common concern in pet parents because onions are a common household food. However, you must never feed your dog onion because it can cause onion toxicity. 

What types of alliums are toxic to dogs?

Why Are Onions Toxic For Dogs?

Can dogs have onions? No, your dog should never eat onions. But why is onion bad for dogs? Onions contain N-propyl disulfide, a sulfuric compound that is toxic to dogs and causes the red blood cells to break down, resulting in severe anemia in dogs.1 

All parts of the onion are toxic to dogs. This includes the leaves, juice, flesh, and even processed powder you use to flavor food.2 It doesn't matter whether it's raw, cooked, fried, or powdered; all onion is toxic to dogs. 

Onions are part of the allium family, which includes garlic, shallots, chives, and leeks, all of which are extremely toxic to dogs.1 Garlic is especially potent with the toxic compound, making it even more dangerous to your dog. Therefore, not only should your dog stay away from onions, but they should never eat any part of these related plants. 

Additionally, all types of onions are dangerous, no matter the color. Therefore, white, yellow, red, and green onions are all toxic to dogs and can put your dog at risk of poisoning and even death. Onion powder is especially concentrated, and even a small amount can lead to onion toxicity. Unfortunately, many foods contain onion, garlic, and onion or garlic powder since they're known for their distinct flavors. 

You may think that your dog won't go for any onion that falls on the floor because it's potent. However, dogs love strong-smelling foods like cheese and onions, so never assume your dog won't try to eat a small piece of onion or garlic that has fallen off the counter while you're cooking. Always keep onions away from your dog, even small pieces, to prevent them from eating them and becoming ill. 

Signs Of Onion Toxicity In Dogs

Onions and dogs don't mix. While you may think onions are delicious, you should never let your dog eat them, even a small piece of onion that has fallen on the floor. Of course, the smaller your dog, the less onion it takes to cause toxicosis. If you believe your dog has consumed onion, no matter how much, talk to a vet as soon as possible. 

Signs of onion toxicity in dogs

When dogs eat large amounts of onion, symptoms can set in quickly, with symptoms noticeable after about a day. However, for smaller portions, you may notice symptoms of onion toxicity within a few days. Symptoms include the following: 

Vomiting and diarrhea can also cause your dog to become dehydrated, which, alongside anemia, can be incredibly dangerous for dogs. Treatment for onion poisoning in dogs is necessary as soon as possible because, without it, organ failure will set in, leading to death. 

Medical Complications From Ingesting Onions 

Your dog will need immediate treatment for onion poisoning, so don't wait to take them to the emergency vet for potentially life-saving treatment. The toxic compound in onions damages the red blood cells, causing their destruction. This process results in several life-threatening medical complications, including the following:

  • Anemia: Anemia is a direct result of the destruction of red blood cells in a process called hemolysis. It may also lead to discoloration of your dog's urine.2
  • Organ failure: Organ failure occurs because the destroyed red blood cells can no longer properly carry oxygen to them. In severe cases, organ failure can lead to death, so immediate treatment is crucial.2
  • Need for oxygen supplementation: Since anemia prevents the organs from getting the oxygen they need to survive, your dog will need oxygen supplementation to give those organs oxygen and prevent organ failure.2

Treating Onion Poisoning In Dogs

If your dog ate onion, take them to the nearest emergency vet clinic as soon as possible to prevent organ failure. Even if you don't think your dog ate enough to harm them, they should be evaluated by a vet. Additionally, if you're unsure whether or not your dog ate any onion, you should still consult a vet to ensure they haven't consumed a toxic amount. 

Diagnosis of onion poisoning is typically easy for a vet through blood samples. However, if you're positive your dog ate onion within the last two hours, your vet will likely induce vomiting without testing to be on the safe side. The longer the toxin stays in your dog's body, the more damage it can do, so inducing vomiting as soon as possible is crucial. However, inducing vomiting is only possible within the first few hours of ingestion before the dog starts digesting the toxin. If you must induce vomiting at home, you should call a vet and have them walk you through the process to ensure you do it correctly. Other treatments for onion poisoning in dogs include:

  • Activated charcoal
  • IV fluids
  • Blood transfusion2

Luckily, most dogs that receive treatment recover from mild onion toxicity and don't experience any long-term effects.2 

Of course, the best treatment for onion toxicity is prevention. Never let your dog eat onion or garlic in any form. 

FAQs

How much onion is toxic to dogs?

Onion poisoning typically occurs in pets that consume 0.5% of their body weight in onions in any form, including raw onion or powdered onion.2 When dogs ingest a lot of onion, it can be fatal to them because it causes anemia. Of course, the amount of onion that's fatal to your dog depends on their body weight. Therefore, smaller dogs are at a higher risk of onion poisoning with fatal complications because they don't require as much onion for it to be toxic. 

Even small amounts of onion can be fatal to dogs, so it's important not to feed your dog any foods that contain onion or garlic, even if you can't actually see the ingredient in it. Just because you don't see any garlic or onion doesn't mean it's not there; many foods contain onion or garlic powder, such as soups, stews, and even salad dressings, which can be toxic to dogs and cause dangerous anemia.

How long does it take for onion toxicity to occur in dogs?

Onion toxicity doesn't cause immediate symptoms because it takes time for your dog's body to digest and react to it. However, symptoms typically develop within 24 hours after ingesting onion. However, they can also take up to seven days after the food has been ingested. Some symptoms, such as vomiting and diarrhea, will be apparent after one day, but signs of anemia can take many days. 

Can dogs eat chicken broth with onions?

No, you should never feed a dog anything with onions or garlic, even in powdered form. Even if your dog eats a small portion, it can lead to health complications. You should always check the food items you share with your dog, especially if it's human food, to ensure it doesn't contain any potentially toxic ingredients. 

Since broth is a popular food item for dogs, often used to help dogs stay hydrated or entice them to eat their food, you should always be careful when bringing home broth from the grocery store. Always check the ingredient label for anything that could be potentially toxic. Most broths contain seasonings, so you may have to find broth made specifically for dogs if you intend to give them broth. 

Dog owner walking dog while carrying a bag of groceries

Final Notes

Onion is incredibly toxic to dogs and requires immediate treatment to prevent deadly anemia and organ failure. Because many foods contain onion, you should never feed your dog any human food without first checking the label. Unlike other toxic foods, the reason behind onions' toxicity is a known chemical compound, and the toxic amount of onion has been found to be 0.5% of the dog's body weight. 

Even a small amount of onion in any form can be harmful to your dog, so you should avoid feeding them any foods that contain onion. Unfortunately, onions aren't the only poison you have to worry about as a pet parent. There are many other poisonous plants that can affect your dog's health. If you think your dog has consumed a toxic substance, contact your emergency vet or call the Animal Poison Control Helpline ASAP.

Need nutritional advice? Want to have a pet health question answered from the comfort of home? Talk to a Dutch vet. We can help diagnose and treat a variety of pet health issues online, no vet clinic hassle needed.

References

  1. Burke, Anna. “Can Dogs Eat Onions?” American Kennel Club, 4 Aug. 2022, https://www.akc.org/expert-advice/nutrition/can-dogs-eat-onions/.

  2. “Can Dogs Eat Onions?” PetMD, https://www.petmd.com/dog/nutrition/can-dogs-eat-onions.