Are onions bad for dogs

Are Onions Bad for Dogs? How to Handle Onion Toxicity

Onions are a staple of the culinary world, as they add great flavor and depth to many dishes. They pair with everything from meat and fish to eggs, pasta, and vegetables. At home, you might use onions to spice up a sandwich, salad, soup, casserole, pizza, or just about anything else. But are onions safe for dogs?

No, onions are not something your dog should eat. In fact, they're one of the most dangerous human foods out there for our canine companions. It turns out that ingesting too much onion can damage a dog's red blood cells, possibly leading to a serious medical issue called hemolytic anemia.

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Let's take a closer look at onion toxicity in dogs so that you know what to have your pet avoid, what onion poisoning might look like in your pooch, and what to do if your dog accidentally ingests the dangerous vegetable.

Why Are Onions Bad for Dogs?

In the case of certain toxic foods for dogs, like grapes, experts don’t know precisely why those foods are harmful. With onions, though, the answer is clear.

Onions contain a chemical that’s toxic for dogs called N-propyl disulfide. This chemical is a sulfur compound, and it's at the root of why onions are so dangerous for dogs.

N-propyl disulfide attaches to the oxygen molecules of your dog's red blood cells, causing oxidative damage. This prevents the red blood cells from carrying oxygen properly. That's harmful enough on its own, but it also tricks your dog's system into thinking that its own red blood cells are dangerous. In this way, your dog's body attacks the red blood cells in a process called hemolysis.

Hemolysis, when left unchecked, will lead to hemolytic anemia. This means that your dog's red blood cells are being destroyed faster than they can be made, leading to serious symptoms of poisoning and even death without treatment.

All Parts Are Poisonous

Every part of the onion is poisonous, including the leaves, flesh, skin, and even the juice. Also, it doesn't matter whether the onion is cooked or raw. Cooking an onion does not remove the disulfide chemical, so it's just as dangerous for your four-legged friend.

It's important to note that all types of onions are dangerous. White onions, yellow onions, red onions, green onions ... none of them are safe for Rover. Additionally, different forms of onions all put your dog at risk. Onion powder is especially dangerous, and other forms — dried or dehydrated, fried, juiced, etc. — put your dog at risk as well.

Related Foods That Pose a Threat

Onions are a member of the allium family of root vegetables. The alliums include garlic, shallots, leeks, scallions (also known as green onions) and chives. Every one of these vegetables is dangerous for your dog. In fact, garlic has a higher concentration of N-propyl disulfide than regular onions, so it can harm your dog even faster.

Keep in mind that many, many foods contain onions, garlic, or onion or garlic powder as an ingredient. Your dog might not chow down on an entire onion that fell onto the kitchen floor — although that's entirely possible — but he or she will definitely go after that tasty onion ring, or a bit of that breakfast quiche.

Signs of Onion Toxicity in Dogs

Beagle looking at camera

If your dog eats a large amount of onions or related foods in a short time, toxicity could set in quickly. But it's more common that symptoms appear a few days after ingestion.

It's also possible for N-propyl disulfide to build up in the blood slowly over time, thanks to your dog eating small amounts of an allium-family food over an extended period.

What Are the Symptoms of Onion Toxicity?

Symptoms of onion toxicity include:
  • Lethargy
  • Loss of appetite
  • Pale gums
  • Elevated heart rate and/or respiratory rate
  • Vomiting
  • Diarrhea
  • Ataxia (a lack of coordination)
  • Discolored urine

Without treatment, a dog suffering from onion poisoning may experience kidney failure or even death.

How Much Onion Does It Take to Poison a Dog?

Another reason that onions and other alliums are dangerous is because it doesn't take a lot to cause serious health problems in dogs. Generally speaking, toxicity occurs when a dog ingests more than 0.5% of their body weight in onions at one time.

To put it simply, even a small amount of onion, garlic, or other toxic allium food can poison a dog easily. The smaller the dog, the greater the danger — eating a small bit of onion might not harm a 150-pound mastiff, but it can cause serious health symptoms in a 10-pound dog like a chihuahua.

Treating a Dog Suffering From Onion Toxicity

Copper colored dog staring in the distance

If your dog is exhibiting the above symptoms and you know or suspect that he or she has ingested onions or a related food, take them to the vet's office as soon as you can. Time is of the essence when dealing with any case of poisoning, including onion poisoning.

Diagnosing Onion Poisoning

Your veterinarian will diagnose your dog based on a combination of test results, symptoms, and a health history that includes eating onions. Hemolytic anemia is detected with a microscopic test that looks for Heinz bodies on a blood smear. When that test result is combined with known recent onion exposure, onion toxicity can be definitively diagnosed.

Treating Onion Poisoning

Your veterinarian might use a variety of treatments to stabilize your dog and return him or her to full health. The stomach may be flushed to remove the remaining toxin, or vomiting may be induced. Sometimes, activated charcoal is administered to absorb the toxin in the gut. Intravenous fluids may be given to help flush your dog's bloodstream and maintain proper hydration. Then, your pup will be monitored closely until the body starts producing enough healthy red blood cells again.

In severe cases of onion poisoning, oxygen supplementation and a full blood transfusion may be necessary.

Generally speaking, the outlook is good for a dog who receives early veterinary care. Remember: Time is of the essence, so if you know or even think that your dog may have gotten hold of onions or something containing onions, act quickly. Take them to the vet's office right away, because it's always better to be safe than sorry.

So, Can Dogs Eat Onions? Keeping Your Dog Safe in the Future

Are onions bad for dogs? Yes, they're one of the most harmful human foods for our four-legged friends. What makes them even more dangerous is the fact that they're so widespread. You'll find onions in one form or another in everything from risottos and gravy to tacos and baby food. Plus, it only takes a small amount to make a dog sick.

There's only one foolproof way to keep your dog safe from onions, garlic, and the other members of the allium family: Tightly restrict your pooch's access at all times. Pay careful attention when you bring onions home, and when you're preparing food with onions, garlic, chives, leeks, or shallots, so that your dog can't eat pieces of these foods or any dishes that contain them. It's safest to keep your dog out of the kitchen entirely when you're preparing a meal.

Onions aren't the only vegetable out there that's dangerous for our canine friends. In fact, there are many vegetables and fruits that can harm dogs, as well as several that are safe. Make sure to do your research so that you know what you can and can't give your beloved companion.


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