What Happens If A Dog Eats Onions?

onion lot

Key points

  • Onions are very dangerous for dogs because they contain N-propyl disulfide or thiosulfate, which causes a shortage of red blood cells and can lead to anemia and hemolytic anemia.
  • If your dog is experiencing lethargy, red urine, pale or bluish gums, elevated heart rate, loss of appetite, vomiting, and panting, it may indicate that the pet has onion poisoning.
  • Garlic, leeks, shallots, scallions, and chives are dangerous to your dog as they contain the same toxic substances as regular onions. Onion and garlic powders can be even more harmful than fresh onions.
  • If you saw your dog eat onions or suspect that the pet may have ingested some, take it to the vet as soon as possible. The doctor will run some blood tests and urinalysis to determine how severe the issue is.
  • Usually, onion poisoning in dogs is not fatal, but it can cause serious conditions such as anemia, Heinz Body Anemia, and allergies.

Onions are one of the products you need to keep as far away as possible from your dog. Unfortunately, the fact that they are so widely used in human foods makes them even more dangerous. Ingesting even a little bit of onion can be life-threatening for your dog.

Why Are Onions Poisonous For Dogs?

N-propyl disulfide or thiosulfate, a compound found in onions, causes the disintegration of red blood cells in the canines’ blood because their bodies lack a particular enzyme needed to digest this molecule. In particular, this N-propyl disulfide attaches to hemoglobin, the oxygen-transporting protein in red blood cells, and decreases their ability to transport oxygen in the body.

brown onion lot

This can result in hemolysis, a condition where red blood cells are destroyed. This happens because the body perceives its own cells as invaders and activates white blood cells to destroy red cells faster than they can be produced. This can lead to regular anemia or hemolytic anemia and many other health problems. In addition, as soon as hemoglobin is oxidized by molecules contained in onions, it will form so-called Heinz bodies, which are essentially clumps in the cell. This significantly reduces the red cells’ ability to carry oxygen through the body.

Is Onion Powder Harmful To Dogs?

Interestingly, onion and garlic powders are even more harmful than fresh onions. So make sure that you check the label for the presence of garlic or onion powder in your food before sharing it with your pet.

Keep in mind that there is no particular part of the onion that is toxic to dogs. The entire vegetable, including flesh, juice, and leaves, contains dangerous compounds and onions are toxic to your dog in any state, including fresh, cooked, fried, or powdered.

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Dogs often get poisoned by onions and onion powder in baby food, as small children always try to share their meals with pets. Be aware that all vegetables that belong to the allium family, including garlic, leeks, shallots, scallions (green onions), and chives, contain the same toxin and are harmful to your pet. Garlic contains even higher levels of the toxin than onions, so it will harm your dog faster.

Sharing Broth Cooked With Onions Isn’t A Good Idea

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Sharing any food cooked with onions with your dog can potentially result in onion poisoning. A small amount of onion won’t hurt your dog, but it’s better to avoid sharing your food anyway. If you buy a pre-made broth or anything you would like to share with your pet, make sure to check the labels for any onions, onion powder, and onion juice.

How Much Onion is Dangerous For A Dog?

Even a small amount of onion can make your dog sick. For instance, it takes half an onion for a 45-pound dog to get poisoned. Usually, a dog develops onion poisoning if it ingests more than 0.5% of its body weight in onion. In most cases, the reaction to onion ingestion is individual and depends on many factors, including the dog’s size, the amount of onion it consumed, and many biological factors.

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If your dog eats a small amount of onion on one occasion, the chances are that it will be fine. However, frequent consumption can provoke the development of many health issues. Regardless, if your canine consumes a large amount of onion at once or small amounts of the vegetable regularly, it will develop anemia, so it’s essential to get medical help right away.

Symptoms Of Onion Poisoning In Dogs

These symptoms don’t particularly indicate onion poisoning. However, if you know that your canine has consumed any type of onion and now it’s displaying any of the symptoms below, it most likely has onion poisoning:

  • lethargy
  • red urine
  • loss of appetite
  • pale or bluish gums
  • vomiting
  • panting
  • ataxia (a lack of coordination)
  • elevated heart rate

Onion poisoning can also lead to asthma attacks, diarrhea, anemia, various allergic reactions, and dermatitis. Heinz Body Anemia or Hemolytic anemia is the most dangerous result of onion ingestion in dogs, as it leads to the shortage of red blood cells.

These symptoms take a few days to appear. The severity of the symptoms will depend on how much onion your dog consumed, the amount of time since the ingestion, and the dog’s size. But if you are sure that your canine has eaten onions or you find some onions missing, take it to the vet immediately to prevent further consequences.

Interestingly, it’s less dangerous for a dog to eat a lot of onion at once than to eat a small amount regularly for a prolonged period of time. Your veterinarian will run some blood tests and diagnose your dog’s condition based on the symptoms. The doctor may put your dog on meds to provoke vomiting to minimize the amount of toxins absorbed in the bloodstream.

Diagnosing Onion Poisoning

woman in white shirt holding brown and white dogOnly a vet can diagnose onion poisoning in dogs. Getting an official diagnosis is vital because the same symptoms can indicate many other health conditions. The specialist will run a blood test to determine the red blood cell count. The test can also show whether hemoglobin clumps have formed on the surface of red blood cells, as they usually appear purple. Your vet can also run a urinalysis to check the amount of hemoglobin in the urine or examine your dog’s stool for onion particles. Heinz body anemia is visible in blood tests even before the red cell count drops, so it’s essential to act quickly.

What To Do If Your Dog Ate Onions?

First and foremost, don’t give onions to your dog and keep all foods that may contain them out of its reach. If you are even a little bit suspicious that your dog has eaten onions, seek veterinary help immediately. Your vet will determine the dog’s condition and decide on the treatment.

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The amount of time that has passed since the dog ingested the onion is crucial. If you bring your pet to the vet immediately after consumption, he’ll induce vomiting and flush your dog’s stomach to prevent onion absorption in the blood. He may also give activated charcoal to reduce the risk of allergic reaction. You should also monitor your dog’s condition for some time after the incident and make sure it stays hydrated.

However, if the dog has more severe symptoms, the vet will treat liver damage, administer fluids directly into the dog’s bloodstream, and carry out blood transfusions if necessary. Sometimes, supplemental oxygen is needed to help with the reduced circulation of red blood cells.
Your vet may need to keep your dog overnight. Once the dog is discharged, you will be given instructions for further care. Onion poisoning can be fatal in some cases, so it’s best to take your pet to the vet as soon as you notice any symptoms.

Healthy Vegetables For Dogs

Onions are a big no for dogs, but there are many safe vegetables you can share with the pet, including broccoli, carrots, Brussel sprouts, celery, green beans, peas, and spinach. These don’t pose any danger and can be a perfect snack or addition to your canine’s meal.variety of vegetables


How much onion can kill a dog?

Onion poisoning occurs when your dog ingests more than 0.5% of its body weight in onions at one time.

Can one onion ring kill a dog?

One onion will likely not kill your dog, but dogs should never have onion rings. They are even more harmful than a fresh onion.

How long after eating onion will a dog get sick?

Vomiting and diarrhea will occur within a day, but other symptoms may take several days to appear.

Can a dog recover from eating onions?

Yes, onion toxicity is not fatal for dogs in most cases, but it may have severe consequences and cause health issues, so take your dog to the vet immediately.

What can I give my dog if it ate onions?

If your dog ate onions, take it to the vet immediately. The doctor will prescribe treatment based on your pet’s condition. Most likely, it will be necessary to induce vomiting and give the pet activated charcoal.