Can Dogs Eat Onions? Absolutely NOT, and Here’s Why

Onions, together with onion powder, are integral ingredients of many dishes we humans taste with absolute pleasure. From soups to mouth-watering sauces, onions can bring unforgettable flavor to numerous culinary things.

As a sparkle in the kitchen, onion attracts some pet parents to add it to their dogs’ diet. If you are among those people who paused for a second before doing culinary masterpieces for their four-legged friends and asked themselves, “Can dogs eat onions?” get ready to be surprised.

Keep on reading and learn everything you need to know about the relationships between dogs and onions.

Can Dogs Eat Onions?

Let’s make things clear straight away: dogs can't eat onions under any circumstances. These vegetables are incredibly toxic for our four-legged friends and may, in extreme cases, be fatal for them. Let's find out why.

Onions contain a chemical called N-propyl disulfide, which is highly toxic for canines. This chemical causes oxidative damage by binding to a dog's red blood cells. In this way, the red blood cell membrane becomes fragile, resulting in hemolysis, or, in other words, the destruction of red blood cells.

Red blood cells are essential for supplying oxygen to the rest of your pup's body and removing carbon dioxide. When destroyed, vital organs will lack oxygen and thus stop functioning properly. In extreme cases, this can lead to organ failure and death.

What Parts of the Onion are Toxic to Dogs?

Bad news: all parts of the onion and onion plant, including the leaves, juice, bulb, and even processed powders, are toxic to canines. Whether it's leeks, shallots, yellow onions, red onions, or green onions – there is no existing form of the mentioned vegetable that can be added to your pet's diet or treats.

An interesting fact: dried or powdered onion is even more poisonous for your four-legged friends than its parts. The reason for this is that it's more concentrated, or, so to say, potent.

When buying any human food you are planning to feed to your dog, always check the label. Both onion or garlic powders should be number one on your list of “don'ts.” This also refers to cats, which are even more exposed to toxins from the Allium family. 

Can Dogs Eat Cooked Onions?

As any cooking method may eliminate onions' toxicity levels for dogs, no form of onion, whether raw, cooked, or fried, is safe. Avoid including it in your dog's diet.

How Much Onion Is Toxic to Dogs?

The fact that it doesn't take much for dogs to experience serious health issues makes onions and other alliums extremely dangerous.

Generally speaking, onion poisoning is identified when a dog consumes more than 0.5% of their body weight at a time.

Now, let's talk about onion size. One medium onion weighs approximately 0.5 pounds and may produce about one cup of diced onion or be equal to one tablespoon of onion powder. Now imagine that it only takes 0.25 pounds of onion (just half of a medium one) per 44 pounds of a dog's weight to cause toxic effects, meaning that a Bulldog, for instance, would only need to eat half of a medium or large onion to experience detrimental toxicity levels.

Even a little bit of onion can easily cause severe poisoning. The smaller the dog, the bigger the danger — consuming a small amount of onion might not become detrimental to a 100-pound Akita, but it can cause serious clinical signs in a 15-pound Spitz.

You should always mind where you keep your onions and other alliums and make sure to store them away from your four-legged pet.

Signs of Onion Toxicity in Dogs

Onion poisoning in dogs entails a range of various clinical signs, which may occur within a day, but sometimes it takes a few days for the symptoms of anemia to become apparent.

If your pup has eaten just a bit of onion, it will likely have mild clinical signs, including decreased appetite, nausea, vomiting, diarrhea, and drooling.

If your pet has consumed a larger amount of cooked or raw onions, it may result in more serious clinical signs, which will likely appear within a few days. Weakness, elevated heart rate, pale gums, red-colored urine, kidney damage, and even death are the signs of anemia.

If you’ve noticed your dog has eaten an onion, please don’t wait for the first symptoms to appear and take your four-legged friend to the vet immediately for diagnosis and treatment. A quick response can make a world of difference.

Your vet will determine your pet’s condition based on their symptoms and blood work. If your veterinarian detects hemolytic anemia or the presence of Heinz bodies on a blood smear along with a recent history of onion exposure, then all signs will refer to onion toxicity.

What If Your Dog Ate Onions?

The most important thing is not to try inducing vomiting on your own unless you've been specifically instructed to do so by a vet. If done wrong, this can harm your dog.

If you suspect your four-legged companion has consumed onions or you saw them eat the vegetables, don't wait to seek veterinary care. The first and most important thing you should do is to determine how many onions or onion-containing products your dog has eaten. This will impact the further treatment plan.

Treating Dog Onion Poisoning

The sooner your dog’s treatment begins, the more likely they will avoid the severe health consequences of onion toxicity. A fast reaction is key here.

A probable treatment plan will depend on how much onion your pup has consumed and when they had it. Suppose you’ve noticed that your dog has eaten onion and managed to get them to the veterinarian pretty soon. In that case, the vet will first induce vomiting to get the vegetable out of your dog’s system before it can be digested. Yet, this only works if the action is taken quickly enough.

If your dog has symptoms of onion poisoning, it will need supportive treatment. A veterinarian can also recommend repeating blood work for about a week, as red blood cell destruction may take a few days to appear on bloodwork. If there’s a skin infection, bathing may be necessary too. Ongoing care will help return your pup get back to a healthy self.

A blood transfusion and oxygen supplementation are essential if your dog develops anemia. So don’t drag your feet, and remember that time matters.

Other Toxic Vegetables for Dogs

Apart from the whole Allium family, including garlic, onions, leeks, chives, scallions, and shallots, there are other vegetables you should avoid feeding your dog.

They include rhubarb, which contains oxalates and may cause serious issues with your dog's nervous system, digestive tract, and kidneys.

Also, watch out for unripe tomatoes, asparagus, mushrooms, and unripe, green, or raw potatoes.

Of course, occasionally sharing a bite of asparagus is unlikely to cause trouble, but a handful of unripe tomatoes could be deadly. So consider this list when choosing foods to share with your dog.

Healthy Vegetables for Dogs

Fortunately, not all vegetables are toxic for dogs. There is a number of pup-friendly ones, which may be not only delicious but also nutritious for your four-legged friends.

For instance, beets. When in moderation, cooked or fresh beets are highly beneficial for dogs. They contain vitamin C, manganese, fiber, folate, and potassium. These nutrients help aid in digestion, boost an immune system and support healthy skin and coat.

Spinach is a source of vital minerals and vitamins, including B6, B9, C, K, and E, also potassium, magnesium, high amounts of carotenoids, folic acid, iron, and calcium.

Carrots, green beans, celery, broccoli, sweet potatoes, cucumber, and butternut squash are also on the list of dog-friendly vegetables.

The Bottom Line

Onions, together with other representatives of the Allium family, like garlic, leeks, and chives, are highly toxic for your beloved four-legged companions. 

That's the chemical called N-propyl disulfide that makes vegetables dangerous for dogs. The chemical results in hemolysis, or, in other words, the destruction of red blood cells. 

The common symptoms of onion toxicity are decreased appetite, nausea, vomiting, diarrhea, and drooling. In serious cases, these are elevated heart rate, pale gums, red-colored urine, kidney damage, collapse, and even death.

If your dog has eaten onions, react as fast as you can! Take your pup to the veterinarian immediately for diagnosis and treatment. Remember: a quick response can make a world of difference.