How Much Onion Can Kill A Dog?

Dogs often love to take a taste of human food. Unfortunately, this innocent habit can turn into a fatal mistake. Not all human foods are appropriate for dogs so owners should be careful and aware! 

So, can dogs eat onion, and how much onion can kill a dog?

It takes 5 grams of onion per kilogram of dog weight to kill a dog. That converts to under 1 ounce of onion per pound of dog weight.

While some dogs may be more resistant to the toxin, others are much more sensitive to the toxin. This leads to variations and actually there is no perfect figure as to how much onion is fatal for a dog. 

Can Onion Kill A Dog? 

Yes, onions can kill a dog. Every part of the onion is rich in toxic compounds. If not caught in time, the prognosis can be heartbreaking.

The dog will lack oxygen in his blood causing his body and internal organs to collapse and fail. The liver and kidneys being the most important ones can lead to death if they fail. 

Can Dogs Eat Onions At All?

No, dogs should not eat onions.  He would not eat raw onions unless he accidently ate some while playing with an onion.

This makes it important to ensure onion products are out of your dog’s reach! But, what about cooked onion human foods? He is likely to eat cooked onion in a tasty dish. Something like mushroom and onion gravy on a steak might tempt him! 

Given that onion is cleverly concealed in human foods, it is not a good idea at all to feed it to your dog. He may easily take a liking to it and eat too much. Meaning he will also probably consume too much onion as well.

As a pet owner, you should be watchful.

Want to find out if ginger has the same effects on dogs? Find out if Dogs Can Eat Ginger?

What Part Of Onions Are Toxic To Dogs?

Apart from giving bad breath and making your eyes water, onions seem harmless for us humans. But for dogs, it could very well spell their death! 

The entire onion bulb is toxic and it only gets more toxic in its dry form. This is because the toxic elements are present in an increased concentration in their fresh form.

Onion leaves, onion bulbs, onion juice, and even onion powder is toxic for dogs. 

Even if the onion is cooked, the toxin remains active and dangerous. This can be alarming since many human foods have onions even in a concealed form.

Although it may not be mentioned, but onion is present in almost every human food, or at least onion powder is! It is a popular flavorant that even features in chips and some other dry foods.  

Toxicity must run in the family when it comes to bulb vegetables of the Allium family. Onions, chives, shallots, garlic all feature toxic elements to the dogs. Meaning owners who eat food with these ingredients, cannot share it with their pet pals. 


What Makes Onions Toxic To Dogs? 

When people hear onion is toxic to dogs, they usually expect this happens for its raw form only.

This is not the case with onions. Onions are toxic for dogs, raw or cooked, fresh, dried, or powdered! 

This is because throughout these onion forms, the toxic compound N-Propyl Disulfide exists and in high quantities.  

It’s not just onions, it’s garlic too! How much garlic can kill a dog?

How Do Onions Affect Dogs?

So what’s so bad about this compound, N-Propyl Disulfide? It acts as an antioxidant in a dog’s blood. When it comes into contact with their red blood cells, they damage these vital oxygen-bearing cells. 

Red blood cells (RBC) are small cells that carry hemoglobin. These haemoglobin proteins carry oxygen and are responsible for transporting blood throughout the body.

N-Propyl Disulfide damages these cells by initiating hemolysis (breaking down of RBCs in the blood), rendering them incapable of delivering oxygen to the body.

Furthermore, it tricks the body into marking the platelets as foreign bodies. This triggers the immune system into attacking these vital cells. This all has a possible fatal effect on a dog if treatment and diagnosis is too late.

Symptoms Dogs Experience After Eating Onion

Onions feature high amounts of N-Propyl Disulfide. Although this compound is edible for humans, it is not safe for your dogs. A dog can show many symptoms after eating onions but it can be hard to pinpoint the cause. 

Symptoms include:

  • Pale gums (especially during exercise)
  • Fatigue and weakness
  • Red urine
  • Reduced stamina and appetite 
  • Heavy panting
  • Elevated heart rate 
  • Vomiting
  • Diarrhea
  • Fainting 

How Long Does It Take For Onion Toxicity To Affect Dogs? 

Generally, the symptoms start to arise in a matter of 1 to 3 days. But there is no strict time period of onion toxicity since it greatly depends on certain factors. These factors include:

Dog Age

Young and old dogs can be affected faster due to compromised immune systems.


Extremely lightweight dogs are affected faster due to the lower amount of onions required to poison them. Heavier dogs will require a higher quantity of onion to take effect and effects might occur several days later. 

Onion Amount Eaten

The more onion your dog ate, the sooner the symptoms will start to show.

Health Of The Dog

Dogs in poor health will suffer from onion toxicity sooner than a dog that is in excellent health. 

Symptoms starts off mild with just the less concerning signs. An upset stomach, vomiting, and diarrhea are the most common initial signs of onion poisoning. 

After struggling with these symptoms, your dog’s health will deteriorate due to the onset of anemia.

Anemia in dogs is a blood condition in which the body has a greatly reduced number of Red Blood Cells.

These RBCs are what transport and circulate oxygen to the whole body. Without these blood cells functioning to their full capacity more, side effects are a real possibility. This includes panting, weakness, and high heart rate. 

Eventually, the immune system will treat the RBCs which have undergone damage as foreign objects and attack them. These damaged RBCs and the anemic condition are what lead to liver and kidney issues. Imminently, extreme damage to the liver and/or kidneys is what can kill a dog! 

But, even if your dog has reached a serious stage in onion poisoning, treatment is available. 

Steps To Take If Your Dog Has Eaten Onion

Human foods have concealed ingredients and may easily contain onion. Also, you cannot watch your dog 24/7 and never know what he might eat.

Knowing what to do if your dog suffers from onion poisoning is crucial. Follow the below steps to make sure your dog pulls through.

Don’t Panic

If your dog has consumed onion, it is important to remember not to panic. Even if your dog is lying down unresponsive, panic can cause you to make wrong decisions. Given the situation, you need to make the best decisions for the sake of your dog.

Remain calm and focus on the next best course of action to take to avoid any more harm to your dog.  

Remove Onion From The Area

If the scene makes it evident that your dog has consumed onion, remove the onion from the area to prevent your dog from consuming any more onion. Doing this also helps to protect any of your other pets from consuming the poisonous bulb!  

Once the area is secured, you can think about moving onto the next step which is to assess the real damage of the situation. 

Try To Assess The Consumed Amount

To know where you stand, it is important to try to calculate the amount of onion ingested by your dog.

Also try to estimate the amount of time passed since your pooch ingested the onion. Recollecting all these details can help your vet prescribe the best treatment. 

So, how will you know how much onion your dog ate? If you keep full onion bulbs, look to the bulb for a clue. Generally, dry onion bulbs weigh between 45g to 70g depending on their size.

Based on how much of the bulb is eaten, you can make an estimation. Keep these details at hand as your vet will require them to make a medical assessment. 

Call The Vet

Next, once you have some ground to stand on with the details, you can call the vet. Make sure you trust this vet since it could be a life and death situation and you don’t want to have regrets!

The vet will ask a few questions, mostly pertaining to ‘how much’ and ‘when’ the onion was consumed. 

This and perhaps a few more questions can help the vet assess the situation. 

Follow Instructions 

Your vet will definitely give you a few instructions to keep your dog stable while you get your pet to the vet. Make sure you follow these instructions very carefully. Once at the vet, you can put your dog into professional hands. 

The vet will most likely try to make your dog vomit out the onion he has eaten. Although most will come out, some would probably be digested by then. In this case, often products containing charcoal are prescribed. 

This should help to remove the majority of onion that’s left in the intestines. 

How to diagnose Onion Poisoning in Dogs?

Onion poisoning diagnosis starts by knowing whether or not the dog has indeed eaten onion or not. Signs can include symptoms like weakness, lethargy, and pale gums. Once these symptoms are present it is likely the red blood cells have also been affected. 

This makes it easy and logical to do a blood test to ascertain a drop in the RBC population. If proved to be low, a blood test to validate RBC count is the best diagnosis. This test also helps to clarify the severity of the poisoning. 

Under a microscope, RBCs will have purple clumps on them. This is a sure sign of red blood cells that are unable to carry oxygen.

Also, the vet can test a urine sample to detect increased levels of hemoglobin. Levels of these compounds are high in the urine since the toxin damages the cells, causing them to be passed out. 


Can dogs eat chicken broth with onions?

No. feeding your dog chicken broth with onions is not a good choice. Why? Because the onions, even when cooked, contain the harmful toxin that can cause severe anemia.
It is best to avoid using onion in dog food and all other members of the Allium family. Try to rather use dog-friendly vegetable ingredients like carrots, green beans, and peas. 

Can a dog recover from eating onions?

If you catch your dog eating onions and put an end to it fast enough and seek treatment immediately, your dog can recover from eating onions. A factor that also contributes to this is if the vet uses the correct treatment method immediately. 

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