Can Dogs Eat Onions?

can dogs eat onions

Fruits and vegetables are great for your dog … but there are some fruits and vegetables you should always avoid sharing with your canine companion. Onions are one of those “do not feed” veggies for your dog. 

Cooking onions adds a certain something to food. And they have many properties that make them healthy for humans. You’d think that if something is good for you, it should be good for your dog too.

But in fact, onions (along with chocolate, another favorite for us humans) are quite toxic for dogs. 

Why Are Onions Toxic For Dogs?

Onions contain a compound called N-propyl disulfide that is harmless for humans, but can cause red blood cells in dogs to break down. This can lead to hemolytic anemia, otherwise known as Heinz body anemia.

Hemolytic anemia occurs when your dog’s immune system is tricked into thinking that the red blood cells are invaders, so the immune system destroys them. This can be potentially life-threatening, because hemolytic anemia impacts your dog’s red blood cells’ ability to transport oxygen throughout his body.

Special Caution: Certain breeds are more prone to onion toxicity. These are mostly Japanese breeds like Akita and Shiba Inu, who are more sensitive to the hemolytic effects of onion. 

Always avoid giving any dog foods containing any type of onion … including powdered or dehydrated onion. These dried onion products are in many products … even baby food. So always read ingredient labels of any packaged foods you think of sharing with your dog … especially soups and broths.  You should also be careful when composting, throwing out onion scraps, or growing onions in a vegetable garden, and make sure your dog can’t get to them. 

Onions Are Allium Vegetables

Onions (Allium cepa) are part of the allium family of vegetables. Almost every vegetable in this family is toxic to dogs … with one exception, as you’ll see. 

Allium vegetables are … 

  • Onions
  • Shallots
  • Scallions or green onions
  • Chives
  • Leeks
  • Garlic

Garlic is the odd one out because it’s the only vegetable in this family that is not toxic to dogs (except in very large quantities). In the proper amounts, fresh, raw garlic can be very good for your dog, with many health benefits. 

RELATED: Learn the ways fresh garlic can help your dog … 

How Much Onion Will Harm A Dog

Even a small amount of onion can harm your dog.

Onion toxicity in dogs can happen when a dog eats only 0.5% of his weight in onions. For a 75 lb dog, that’s only ¾ of a cup of onions. For a 10 lb dog, 1½ tablespoons is all it takes to cause damage. Lastly, for a 25 lb dog, it will take ¼ cup of onion.

(By the way, cats can’t have onion, either.)

Watch out for onions, onion powder, or any other form of onions as an ingredient in anything you feed your dog. Onion toxicosis can kill your dog

But what if your dog does eat some onions? If you act fast, your dog can recover from onion toxicity …

What To Do If Your Dog Eats Onion

If your dog somehow eats some onion, or food with onions in it, and you don’t know how much onion he ate, it’s best to ask your veterinarian right away.

If your dog just ate a little bit of onion when he cleaned off your beef stew plate, depending on his size, he may be fine. Or your veterinarian might suggest that you induce vomiting to get the onion out of your dog quickly. 

How To Induce Vomiting In Your Dog

Always check with your vet or an animal poison control center before inducing vomiting. Some vomited toxins can damage the esophagus. If she gives you the go-ahead, here’s what to do. Give one teaspoon of hydrogen peroxide to your dog for every 5 pounds of body weight, up to a maximum of three teaspoons per dose. Wait 10 minutes between each dose. If he hasn’t vomited after the third dose, stop giving the solution. 

Your vet may also recommend you give your dog activated charcoal. Activated charcoal will absorb toxins from the gastrointestinal tract … but it has to be given quickly after your dog has eaten onions. You can buy activated charcoal in a dog-specific product, or get capsules from your local health store. Activated charcoal is useful for lots of emergencies, so keep it in your first aid kit

Once the onions have been digested, it’s too late for remedies. And you might not know your dog ate onions. So always be on the lookout for signs of onion toxicity, especially if your dog’s a food thief or garbage raider. 

RELATED: How long does dog digestion take?

Symptoms Of Onion Poisoning

If you didn’t see your dog eating onions, he might already be digesting the onions he ate. 

If you suspect your dog’s eaten onions, watch for symptoms of onion toxicity. And if you aren’t on high alert, you may not know that’s what’s happening. Onion toxicity can occur any time after your dog has started digesting the onions … to a few days after eating onions. So here’s what to look out for. 

Symptoms of onion toxicity or onion poisoning include:

  • Discolored urine
  • Decreased appetite
  • Elevated heart rate
  • Exercise intolerance
  • Weakness
  • Lethargy
  • Problems with balance and movement
  • Fainting
  • Diarrhea or bloody diarrhea
  • Pale gums

Signs Of Anemia

You’ll also want to watch your dog for symptoms of anemia. These signs usually appear a few days after your dog eats onions, so if you know your dog ate a toxic amount of onions, don’t wait this long to go to the vet. 

  • Whitish or pink gums
  • Skin bruising
  • Dark or tarry stool
  • Blood in stool
  • Blood in vomit
  • Fatigue

If you know your dog ate onions, or if your dog is showing one or more of these symptoms of onion toxicity or anemia, call your veterinarian right away. These symptoms can indicate your dog is suffering from a severe onion-related illness.

Diagnosis And Treatment Of Onion Poisoning In Dogs

Depending on your dog’s symptoms and how long it’s been since your dog ate onions, your vet will do bloodwork to test his red blood cell count. This will show if he has Heinz body anemia. Treatment options will also depend on how recently your dog ate onions. 

If it was in the last hour or two and you didn’t induce vomiting, your vet will likely do that, as well as giving activated charcoal to help remove the toxins from your dog’s body. They may also do gastric lavage, to wash the onions out of his stomach. 

If it’s been a few days since your dog ate onions and he has severe anemia, treatment may include the following life-saving measures … 

  • IV fluids
  • Supplemental oxygen therapy
  • Blood transfusion

If this happens, your dog will need to be hospitalized. Onions are high on the list of dangerous foods for dogs, and if not treated fast enough, can lead to anemia which can cause death. If your dog is treated quickly, it’s possible for your dog to survive onion poisoning or onion toxicity.

When your veterinarian allows you to take your dog home, you’ll need to keep a very close eye on him and keep him away from any more onions.

But try to avoid your dog eating onions in the first place. If you’re vigilant about making sure your dog doesn’t have access to onions and other allium vegetables, you’ll avoid onion toxicity in your dog.

References

Harvey JW, Rackear D. Experimental Onion-Induced Hemolytic Anemia in DogsSage Journals. 1985, July 1.

Kovalkovičová N, Šutiaková I, Pistl J, Šutiak V. Some food toxic for petsInterdiscip Toxicol. 2009 Sep: 169-76. 

Beynen AC. Onion in canned dog foodResearchGate. May 2020.

Lee KW, Yamato O, Tajima M, Kuraoka M, Omae S, Maede Y. Hematologic changes associated with the appearance of eccentrocytes after intragastric administration of garlic extract to dogsAmerican Journal of Veterinary Research. 2000 Nov;61(11):1446-50.

Houston DM, Myers SL. A review of Heinz-body anemia in the dog induced by toxins. Vet Hum Toxicol. 1993 Apr;35(2):158-61. PMID: 8470361.

Kovalkovičová, Natália et al. “Some food toxic for pets.” Interdisciplinary toxicology, Volume. 2,3, 2009, Pages 169-76

Gugler K, Piscitelli C, Dennis J. Hidden dangers in the kitchen: common foods toxic to dogs and cats. Compend Contin Educ Vet. 2013 Jul;35(7):E2. PMID: 23677840.

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