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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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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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Pomeranian

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Fifteen Years

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2 found helpful

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Lethargy, Shaking, Back Legs Weak (Never Were Before 2 Days Ago)

My 15 year old dog has heart issues but otherwise in decent health. She ate a White Castle hamburger with onions. A week later after the onion, her back legs are very weak and she is shaky. Could it be onion related?

Feb. 1, 2021

Owner

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Dr. Maureen M. DVM

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2 Recommendations

Hi, It's highly unlikely that the onions are causing the symptoms you are observing. Hind limb weakness could be caused by various factors such as neurological conditions, arthritis, hip dysplasia, tick-borne infections among others. Please visit your vet for a thorough check-up and a more confirmatory diagnosis. Good luck

Feb. 2, 2021

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Airedale Terrier

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Three Years

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5 found helpful

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I cooks onion then took out onion to cook beef. dog ate beef but puked right after gum pink he slow and weezes he about 30lbs thick coll herd dog

Jan. 15, 2021

Owner

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Dr. Linda S. MVB MRCVS

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5 Recommendations

If your dog didn't actually eat the onion itself, there is no real risk of onion toxicity as dogs must eat a certain quantity before we worry. The beef may have been too rich or they may be something else going on such as a viral infection or pancreatitis. If the vomiting continues or your dog seems unwell, a vet visit is best.

Jan. 15, 2021

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Dachshund

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Eight Years

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None

Ate chicken and rice that was made with onion powder. Had a 1/4 cup worth. Entire recipe only had 1/2 tsp. He’s 19 lbs Also his 16 lbs dachshund mix sister and 30 lbs terrier mix cousin ate same amounts

Jan. 11, 2021

Owner

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Dr. Gina U. DVM

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0 Recommendations

Hello Onions can be toxic to dogs. I recommend calling your veterinarian or taking your pet in for an exam. They may recommend running labwork or possibly inducing vomiting depending on the time frame. Good luck.

Jan. 11, 2021

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German Shepherd

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Fourteen Years

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None

My dog ate half a sweet onion

Dec. 13, 2020

Owner

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Dr. Sara O. DVM

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2 Recommendations

Hello, this can make her very sick. It would be best for your dog to see your vet. Your dog may vomit and have diarrhea. This can also cause other internal issues. Your vet will most likely induce vomiting and start your dog on IV fluids

Dec. 13, 2020

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Cocker Spaniel

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Six Months

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Onion Poisoning

My dog ate food with onion and garlic in it. She is now lethargic and throwing up after two days’ time.

Sept. 29, 2020

Owner

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Dr. Michele K. DVM

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5 Recommendations

Thank you for your question, I'm sorry that your puppy is not feeling well. It sounds like your dog's GI tract is very upset, whether it was from the onion or garlic, the food in general, or whether there are parasites or other things happening. Since it's been going on for two days, it would probably be best to have your puppy seen by a veterinarian as soon as possible. They will be able to examine your puppy, see what might be causing this, and get treatment so that your puppy does not become dehydrated and continue to be ill. I hope that everything goes well with your puppy.

Sept. 29, 2020

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Rex

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Labrador Retriever

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3 Years

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Fair severity

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My dog Rex was licking my floor tonight, I was eating a White Castle sandwich earlier which has onions on it tiny slivers of onions oh, and he might have gotten a hold of one I can't really tell oh, I vacuumed the floor right after he licked the floor, he's a Labrador Retriever that weighs around 185 to 190 pounds. he's my best friend and the only thing that reminds me of my grandpa. I don't know what I would do if I lost him. Is there anything I should be concerned about?

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Dozer

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jack russell mix

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2 Years

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I have a dog that ate the outer layer of a medium onion hes 28lbs hes eating drinking do I need to worry this happend due to roommate pulling trash bag out to put out side

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Ruger

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German Shepherd

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4 Years

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So my 110lb german shepard just got in the trash and ate onions off a plate. His breath doesnt smell like onioms, i stopped him but i dont think in time. Of course this is the same dog that ate a plate of hot wings and survived. Should i take him to the vet in the morning or see how he acts?

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Comet

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Whippet

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9 Months

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our 9 month,18 lb. whippet mix puppy got hold of a 1/2 an english muffin with a thin spread of tomato sauce on it. The sauce ingredients include onion and garlic. there were likely 2-3 squares of onion (1/4 in. x 1/4 in.) We know onions and garlic can be toxic to dogs. its 9 pm and our vet is closed. Our puppy isn't showing any symptoms of poisoning. Is it safe to wait until morning and call the vet or should we try to have her seen at an emergency clinic tonight?

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George

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Mastiff

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8 Years

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No Symptom

I gave my two dog some table scraps, then realised that it contained onions. The pie(600g) contained 10% onion. Each dog has eaten approx half a pie. The dogs weigh 40kg mastiff and 25/30kg lab. They consumed the pie about 10hours ago.

Onion Poisoning Average Cost

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

Average Cost

$950

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