Why A Dog Can’t Eat Onion? (A Hidden Threat To Your Dog’s Health)

Onions are widely found in human foods as well as a seemingly harmless kitchen staple. While being a flavorful addition to our meals, you need to understand why your dog can’t eat onions.

A dog can’t eat onions because onions contain a compound called N-propyl disulfide. This compound is highly toxic to dogs and can cause a breakdown of red blood cells in their bodies. This leads to anemia which can be life-threatening.

In this post, we’re here to shed light on the harmful effects of onions on your dog’s health. This will enable you to make informed decisions about your pet’s diet.

Why Are Onions Bad For Dogs?

There is always one chemical compound that is frequently mentioned when the words ‘dog’ and ‘onion’ are mentioned in the same sentence.

And that is N-propyl disulfide.

Besides N-propyl disulfide, another less-mentioned but equally toxic compound in onions is Sodium n-propylthiosulfate.

It is these two compounds that are the main reason for onion toxicity in dogs.

What Happens When Dogs Eat Onions?

The lack of essential oxygen leads to a condition called hemolytic anemia.

The one reason that makes onions so dangerous for dogs is that the above compounds will attack your dog’s red blood cells.

These compounds will rapidly destroy the red blood cells in your dog’s body resulting in the “denaturation of hemoglobin.”

Hemoglobin serves as a crucial part of red blood cells in both animals and humans.

It is high in iron content and its primary function is to distribute oxygen throughout the organism’s body.

When dogs eat onions, this results in the breakdown of red blood cells which means less oxygen being transported to various parts of the body.

The lack of essential oxygen leads to a condition called hemolytic anemia.

Symptoms of anemia include:

  • Breathlessness
  • Pale gums
  • Difficulty breathing
  • Vomiting
  • Panting
  • Lethargy
  • Lack of appetite
  • Blood in urine
  • Passing out

How Much Onion Will Hurt Your Dog?

dog in kitchen with basket of onion in front of it

The amount of onion that can harm a dog depends on the dog’s size, breed and overall health.

But as a general rule, consumption of just 0.5% of your dog’s body weight in onions can potentially cause harmful changes in its red blood cells.

Assuming that you have a dog that weighs 30 lbs (13kg), onion can be potentially toxic when your dog eats 2.5 ounces (70g) of onion.

Even smaller amounts can be harmful over time if consumed regularly.

And the scary part is that there isn’t a lot of onion to begin with.

I can easily use more than that when cooking at home.

Do you know that grapes are also very toxic for dogs?

Just a few grapes is enough to cause serious damage to a puppy or small sized dog.

How to Treat Onion Poisoning In Dogs At Home?

Never induce vomiting in your dog without consulting your vet first.

If your dog ate onions, the first thing that you need to do is to call the vet.

The vet will need to know the weight of your dog and the amount of onion consumed.

If the vet feels that it is necessary to induce vomiting in your dog, this can be done by giving your dog hydrogen peroxide (3%).

This is an antiseptic solution that many of us have at home which works well for cleaning wounds and cuts.

I also keep a bottle at home for my dog in the event I need to induce vomiting.

But if you are able to get your dog to the vet in a short amount of time, that would be the best option.

One important thing to note.

Never induce vomiting in your dog without consulting your vet first.

I will always all my vet to let them know what happened before getting the go-ahead to induce vomiting.

There are some scenarios when induced vomiting can do more harm than good.

Especially when your dog is unconscious or has eaten something sharp.

Only do it under the guidance of the vet.

How Is Onion Poisoning Treated In Dogs?

dog at vet

The vet will give your dog a physical examination and run a complete blood test.

The vet will provide the necessary care and attention until your dog’s body can generate a sufficient number of healthy red blood cells to replace the damaged ones.

In more severe cases, a blood transfusion may be necessary for your dog.

Is Onion Power Dangerous For My Dog?

Besides onion itself, another form of onion that you need to be careful of is onion powder or onion salt.

Onion powder or salt is basically a very concentrated form of onion which means only a small amount is enough to become dangerous for your dog.

1 tablespoon of onion powder is the equivalent of 1 cup of chopped onions (52g/1.8oz).

That means a 30-pound dog only needs to consume slightly more than 1 tablespoon of powdered onion to be in danger.

Be careful when feeding your dog rotisserie chicken as the marinate tends to contain onion powder.

Can My Dog Eat Other Parts Of The Onion?

Your dog should not consume any part of the onion. This includes the bulb, leaves or even onion juice.

All parts of the onion contain toxic compounds that can be very dangerous for all dogs.

How To Keep My Dog Safe From Onions?

Protecting your dog from onion poisoning requires diligence on your part. Here are some tips that can help you avoid accidental onion ingestion:

Keep Onions Out Of Reach

Having a dog at home is similar to having a kid around.

You need to dog-proof your home by making sure that you keep onions and any other dangerous substances under lock and key.

If you have onion plants growing in your garden, be sure to build a fence around them.

Dogs can be as curious as cats and have a greater tendency to eat things that they shouldn’t.

There are dogs that have eaten used pads before as well.

Secure Your Trash

dog digging in the trash bin for scrapes

Dogs are amazing scavengers and love rummaging into thrash for the next juicy treat.

They have developed very strong digestive systems that allow them to eat spoiled meat without falling sick.

But not something that I would recommend or advocate at all for your dog.

Make sure to secure your trash can so that your dog can’t get to the discarded onions.

I make it a point to take out the trash every day and not leave anything in the bins overnight.

Educate Your Household

If you have other family members at home, you need to make sure that everyone knows about the dangers of onions to dogs.

Even if they do not let your dog eat raw onions, many food items and takeaways contain onion powder, including baby food.

Check The Ingredient List

If you are feeding your dog commercial pet food, you don’t have to worry about them containing onion.

But before you give your dog some human food as a treat, please check the ingredient list to make sure that onion isn’t one of the listed ingredients.


Are Cooked Onions Bad For Dogs Too?

Cooked onion rings or caramelized onions are still harmful to dogs. Cooking does not remove the toxins that make onions dangerous to your dog’s health

Why Dogs Can’t Eat Garlic?

Garlic, similar to onions, is a part of the allium family, which also includes plants like shallots, leeks and chives. Garlic is even more potent and is known to be 5x more harmful to dogs.

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