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What is Onion Poisoning?

Allium species, including onions, garlic, leeks, and chives can be toxic to dogs in excessive amounts, or over time. Plants in this family contain organosulfur compounds which account for the distinctive odor and flavor associated with them. These compounds are metabolized into highly reactive oxidants which can damage the red blood cells (erythrocytes) of dogs, particularly certain Japanese breeds like Akitas and Shiba Inus. The oxidants bind directly to the erythrocytes, so these dog breeds are particularly at risk because of the specific chemical make-up of their red blood cells. All dogs are susceptible however, in contrast to humans whose red blood cells aren’t affected by the organosulfoxides. As the oxidant level within erythrocytes become higher than the cells’ antioxidant metabolism capacity, a condition called oxidative hemolysis results which affects oxygen transport and causes red blood cells to rupture and be destroyed. The erythrocytes will be marked by Heinz body formation, an abnormal blood cell visible upon microscopic examination of a blood smear.

Dogs with allium species toxicosis develop hemolytic anemia. Typically the onset is delayed by several days, but large doses may cause symptoms of anemia as little as one day after ingestion. Vomitingdiarrhea and gastrointestinal upset may also be present. The toxic dose is typically 15-30 grams per kilogram of the dog’s weight, or about .5% of the body weight. All types of allium species can cause this toxicity, but garlic is the most concentrated and therefore the most dangerous for dogs. Dried, powdered, and cooked products are just as toxic as those that are fresh and raw. As the condition progresses, the bone marrow will generate new red blood cells and the anemia will pass, as long as no further exposure takes place. High doses might need to be treated with a blood transfusion to avoid fatally low levels of erythrocytes.

Onions, garlic and other members of the allium family can be toxic to dogs. This is called allium species toxicosis, or onion toxicity. Signs may take several days to manifest.

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Onion Poisoning Average Cost

From 61 quotes ranging from $500 - $3,000

Average Cost

$950

Symptoms of Onion Poisoning in Dogs

These signs could indicate your dog has eaten onions or garlic.

  • Smell of onions or garlic on the breath
  • Excessive salivation
  • Irritation of the mouth
  • Vomiting
  • Diarrhea
  • Lethargy
  • Signs of abdominal pain
  • Rapid heartrate (tachycardia)
  • Panting (tachypnea)
  • Weakness
  • Exercise intolerance
  • Collapse
  • Pale or bluish gums

Types

These are the types of products you should keep away from your dog.

  • Garlic – most toxic, about five times as potent as onions
  • Onions
  • Leeks
  • Chives
  • Scallions or green onions
  • Garlic or onion powder
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Causes of Onion Poisoning in Dogs

These are some of the causes and risk factors associated with allium species toxicity.

  • Ingestion of fresh growing onions, garlic or chives
  • Feeding food prepared for humans to a dog
  • Dog chews open a container of dried or powdered onions or garlic
  • Certain breeds are more susceptible (Japanese breeds like Akita and Shiba Inu)
  • Some factors can make the red blood cells weaker and increase a dog’s susceptibility to allium species toxicosis (Zinc deficiency, glucose-6-phosphate dehydrogenase which is an inherited deficiency, and some drug treatments
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Diagnosis of Onion Poisoning in Dogs

If you know your dog has ingested a product that contains onions or garlic this will make diagnosis easier. If the dog is already showing signs of lethargy and weakness, indicators of hemolytic anemia will likely be visible on a blood test. This can also help to indicate the severity of the problem. Urinalysis may show high levels of hemoglobin in the urine. Heinz body anemia may be visible on a blood smear examination even before there is a marked drop in red blood cells. Other signs, like a smell of onions or garlic on the breath (with recent ingestion), or vomiting and diarrhea with undigested pieces may also be an early indication that your dog has allium species toxicosis. For unknown instances of poisoning, the veterinarian may ask what foods you regularly give your dog and suggest you check the list of ingredients.

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Treatment of Onion Poisoning in Dogs

If the poisoning is still recent, vomiting may be induced and the dog may be given activated charcoal to reduce absorption in the gastrointestinal tract. The veterinarian will tell you to monitor your dog for signs of anemia over the next few days and may recommend a diet low in oxidants. If a large amount has been ingested, your dog may need to be kept in a veterinary hospital for that time period. Severely ill dogs will likely need supplemental oxygen to make up for the reduced circulation of red blood cells and a blood transfusion could be necessary to stabilize your dog until the bone marrow is able to generate enough new, healthy erythrocytes.

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Recovery of Onion Poisoning in Dogs

Dogs will likely recover from mild exposure to onions or garlic, but severe poisoning can be fatal, especially without treatment. If you know you dog has eaten an excessive amount of onions or garlic, you should take him to the veterinarian immediately even if there are no immediate signs. 

Avoiding exposure is the best way of managing the condition. If you are feeding your dog any food prepared for humans, check the list of ingredients for onions, garlic or other allium products. Even if your dog remains asymptomatic, continual low level doses will make any accidental ingestion much more serious. Put any spoiled food that contains onion or garlic products through a garbage disposal or place in a sealed trashcan. Take precautions if there are allium species growing in your garden. Dogs don’t normally like the taste of these plants, but it’s safer to keep them out of reach.

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Onion Poisoning Average Cost

From 61 quotes ranging from $500 - $3,000

Average Cost

$950

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Written by a Pugs lover Grace Park

Veterinary reviewed by: Michele K.

Published: 06/24/2016, edited: 03/30/2021

Onion Poisoning Questions and Advice from Veterinary Professionals

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Shoodle

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30 months

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5 found helpful

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Unknown severity

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None

Our dog just ate a small pickled onion I’m on a boat 3 hours from a vet! I’ve given her a good amount of biscuits to induce vomiting What else should I do?

Sept. 27, 2020

Owner

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Dr. Michele K. DVM

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5 Recommendations

Thank you for your question. I apologize for the delay in my response, this venue is not set up for urgent emails. I would not think that that small onion would cause any toxicity. If they are having any vomiting or diarrhea, Since I cannot see your pet, it would be best to have them seen by a veterinarian, as they can examine them, see what might be causing this, and get treatment if needed.

Oct. 13, 2020

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Beagle basset mix

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One Year

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4 found helpful

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Lethargy, Vomiting, Diareah, Loss Of Apetite

Our dog got into a pot of oil that had onion rings cooked in it a couple of days ago, now he's just lying around. He's stopped vomiting but won't eat. Should I get him to a vet? This is day 3 of symptoms.

Aug. 12, 2020

Owner

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Dr. Gina U. DVM

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4 Recommendations

Hello Onions can be toxic to dogs. I recommend taking him to a veterinarian right away. They may want to run lab work and give him medication for the vomiting. Good luck.

Aug. 12, 2020

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Pug

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Seven Years

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3 found helpful

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Vomiting

Ate 3 small pieces of steak with onion powder and steak sauce had onion powder. Pug has thrown up 4 times. Last vomit was 4pm. No diarrhea and has drank water on her own. Still barks when she hears noises

Aug. 4, 2020

Owner

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Dr. Michele K. DVM

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3 Recommendations

Thank you for your question. If she is acting normally other than the vomiting, you may be able to fast her for 12 hours and see if that settles your stomach. If she is not continuing to vomit after that, you should be fine to start feeding her again in 12 hours and see how she does. If she continues to vomit, or is having diarrhea or is lethargic, then it would be best to have her seen by your veterinarian. I hope that she is okay and feels better soon!

Aug. 4, 2020

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Two Years

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Diarrhea

Over the past 2 days Emma has had about a cup to cup and half of chicken stock that had onion in it, got into leftovers a week ago that had a few bits of onion in it. Today she has done about 6 poos, usual is 4. 4 of 6 poos were diarrhoea, heart rate is fine, resp rate fine, no vomiting

Aug. 1, 2020

Owner

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Dr. Michele K. DVM

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1 Recommendations

Thank you for your question. While I don't think that Emma is showing signs of onion toxicity, it does seem that she may be having some GI upset from the food that she has been getting into. It might be a good idea to feed her a bland diet of boiled white chicken and boiled white rice for a couple of days, then ease her back onto her regular diet. If that doesn't help, it would be a good idea to have her seen by your veterinarian. I hope that all goes well for her!

Aug. 1, 2020

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Sam

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Shorkie Tzu

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3 Years

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Hasnt Shown

my dog sam has recently eaten a few pieces of meat coated with spices including onion powder and garlic powder, they were thinly sliced but he weighs approx 9 pounds.

Sept. 16, 2018

Sam's Owner

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Lucy

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miniature dachshund

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12 Weeks

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None

My puppy is a 5 lb mini dachshund. She is going on 12 weeks. We gave her about 2 tablespoons of ground beef with taco seasoning, which turned out to contain onion powder as a main ingredient. Will this harm her? Does she need to see a vet or have induced vomiting? Please help! Thanks.

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Zuzu

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Micro yorkie

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10 Weeks

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Mild severity

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Loss Of Appetite

Please help! My puppy is 10 weeks old. Struggling to have an appetite. Vet suggested boiled chicken and rice. So I made some... but I added a quarter of an onion and one “tooth” of garlic to the boiling water. The one tooth of garlic was quite large. My puppy is 1 lb yorkie. I’ve been having to feed her every three hours and it’s past 3 hours and she is refusing to eat and feels extra warm. I fed her only the chicken and rice. Not the liquid and not the actual onion or garlic ... but the chicken and rice was boiled in this water. Did I poison her?!?!

Onion Poisoning Average Cost

From 61 quotes ranging from $500 - $3,000

Average Cost

$950

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