How much onion or garlic is toxic to pets?

I belong to an online community of veterinarians that is populated with some of the top experts in various areas of veterinary medicine.  They frequently share their expertise and advice.  I found this topic extremely relevant to our daily practice.

Human health supplements are more popular now than ever.  This has trickled into the pet market, too, especially with foods.  We do have to be careful about assuming that human health supplements are safe and/or effective for pets.  In some cases, they can be outright toxic.  We need to be certain that what we’re giving is ok to give.

The mini-essay below is from a toxicologist who is boarded by both the human and veterinary specialties.  She discusses how and why garlic and onions are on the “No” list in almost every case.


Garlic is more potent than onion; it takes about 5 g of garlic per kg of body weight to cause hemolysis in dogs. Cats are much more sensitive as they have more fragile RBCs. That sounds like a lot of garlic, and it is if you’re talking fresh garlic; but powdered garlic or onion are much more potent and more likely to cause toxicosis than fresh. Onion and garlic powder can be present in a lot of foods, but usually in very small amounts. Exceptions would be things like onion-flavored soup or gravy mixes and some baby foods, which can have considerably higher levels of onion/garlic. Cooked onions/garlic are hazardous because they are more concentrated than fresh and usually are highly flavored with what they were cooked with (e.g. liver and onions), so the animal is motivated to eat more of them. I believe the estimation for cats was less than a teaspoon of cooked liver and onions has caused clinical illness in cats. When inducing Heinz bodies for research studies, generally cats are given onion powder at the level of 1-3% of dry matter intake.

Onions/garlic are metabolized in the GI tract to highly reactive oxidative metabolites. ALL ingested garlic/onion will case some degree of hemolysis in dogs and cats–it’s only when sufficient RBCs have been damaged to alter the overall oxygen carrying capacity of the blood and/or to cause hemoglobinuria that the toxicosis becomes clinically evident.

So, does the small amount of garlic that is generally present in pet foods or yesterday’s beef stew cause RBC injury? Yes, but the level of injury is so low that clinically significant illness would not be expected. Some baby foods contain significant amounts of garlic/onion powder and can cause clinically relevant RBC injury if fed chronically to cats. I definitely do not recommend giving garlic tablets to cats or dogs because IF they have garlic in them, they will induce chronic anemia. That being said, most of the garlic tablets on the market that are labeled as “odor free” have had most/all of the organosulfoxides removed in the ‘deodorizing’ process, so would be less toxic. From a toxicity standpoint, I would say that the currently available flea control products when applied per label to the appropriate species are far safer than using garlic (which doesn’t work anyway) to control fleas or ticks.


Sharon Gwaltney-Brant DVM, PhD
Diplomate, American Board of Veterinary Toxicology
Diplomate, American Board of Toxicology


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29 responses to “How much onion or garlic is toxic to pets?

  1. Chris

    If there can be RBC injury from even the small amounts of garlic that’s put in pet food, why is it in there at all? That sounds like spitting into the wind to me.

  2. Pingback: Can dogs and cats eat those Mamee noodle snack? - Page 2 -

  3. I have used brewer’s yeast with garlic added to my cat’s food for years and they are great, and it DOES keep the fleas off. No more boric acid in the rugs and on the furniture. No more toxic expensive nicotine poisons. Win-win.

    • I try not to argue with success, and if this routine controls fleas for you, that’s a win. I will respectfully disagree that it’s a win for your cat’s red blood cells, though. Some of them are damaged by the garlic. Perhaps not enough to impact your cat in a visible way, but damage is done, and his/her body has to cope with that.

      I’m very comfortable with the efficacy and safety of the products we recommend for dogs and cats. I’ve personally seen yeast and garlic fail repeatedly to control fleas on pets at our practice, so it’s not a treatment I reach for first.

  4. Is the amount of onion powder in pedigree dog food cumulative?
    and what sort of problems would be noticed.

    • The amount that might be found in pet food isn’t likely to cause a dog to have signs that we can actually see. Some red blood cells are damaged no matter what. It’s just that dogs and cats have a lot of red blood cells in reserve to replace them. The “toxin” doesn’t stay in the body forever, so we don’t see a cumulative effect.

      Signs of anemia include breathing problems, weakness, fainting, lethargy.

      Hopefully that answered your questions. If not, let me know and I’ll try again. Thanks for commenting on the blog!

  5. Amanda Nolan

    So I just found this out and I gave my dogs some pices of chicken seasoned with a little ms dash original salt free seasoning a few days in a row and I often give some spaghetti with sauce just a little of my plate. both have garlic in them. they’re Chihuahuas are they going to be okay

    • There probably isn’t enough garlic in those foods to cause problems for your dogs. Yes, there is always some damage to red cells, but I doubt you’ll see any illness.

      Steer clear of these foods in the future. :)

      Check the ASPCA web page for more info on toxic foods.

  6. kay

    My cat got on the bench and ate some meat loaf that had onion in it. I am not sure how much she had do you think she will be OK? Also she is nursing three kitten’s would the onion be passed on to the kitten’s through her milk? Thanks for your time. Kind regards Kay

    • It totally depends on how much onion, how much she ate, and what her weight is. It’s probably going to be fine, but watch for any difficulty breathing, lethargy, vomiting, or other ‘sick’ sorts of behavior. If anything changes or she seems ill in any way, contact your local vet and have her examined right away. Dogs and cats have some blood cells in reserve, so if it wasn’t a heavy exposure, you may not even see a problem. Just watch for those signs and have her treated if they occur.

      You can also contact Animal Poison Control via the ASPCA. There’s a charge (about $85), but they will work with you and your vet to resolve the case.

  7. My kitten just jumped onto my counter and ate a small piece of a raw onion I was cutting….pretty sure it was a small piece but she ate it! Should I be worried?

    • I recommend calling your veterinarian or animal poison control. It’s probably not enough onion to cause noticeable harm, but it’s always better to be safe than sorry with very young animals. As with most toxins, the amount ingested and the body weight have a huge influence on what sort of problems you might see. Watch for her being lethargic, vomiting, difficulty breathing, etc. Of course take her in to a vet if those occur.

      • Okay thanks! She seems fine right now, but I’ll be going to the Vet tomorrow. Unfortunately, I live in China and not only are there no animal rights here, the Vets are not very competent (including the difficult language barrier) but I will do what I can!

      • There’s definitely a different view on animal welfare in some countries. Just watch her overnight for those signs. You’ll want them to check her red blood cell count. It’s called a Packed Cell Volume (PCV) or Hematocrit (HCT). It may be done as part of a Complete Blood Count (CBC).

        She’ll probably be fine, but good luck either way!

  8. Interesting article. I feed a commercially available raw diet to my cat and my dog. It contains a 0.001% of fresh garlic according to the ingredient list, I’m assuming to enhance flavor and smell… Should I be worried about even such a low amount?

  9. angela

    I have my cat some baby food with onion powder in it I had no clue that it was toxic that was what the vet told me to buy he only had I’d say about three teaspoons of it one time he was sick so they told me to buy turkey baby food so I did I called them back they didn’t seem concerned said he may just get a belly ache I just got him better I was just wondering with what I gave him is it gonna be toxic to him?

    • It shouldn’t cause your cat enough trouble to be noticeable. The only exception to that might be if he is very anemic (low red blood cell count). Even then, I don’t think there is enough onion in the little bit of food he ate to cause him trouble. If you can avoid baby food with onion or garlic, it is definitely an often-used food to tempt cats that aren’t eating well. There should be some varieties out there that are onion-free.

      I couldn’t quite tell if this was something that happened quite a while back or not. If it was more than a few days ago, and you’re not seeing any problems, you won’t see any. He’ll be fine.

  10. stella Lello

    Hi my question is can cross contamination of onions or garlic hurt a dog like my 4yr old nephew squeezed half an onion that I peeled before I could clean his hands he ran and grabbed the dogs toy and put it in the dogs mouth would the juices from the onion hurt the dog or do you actually have to ingest the onion or garlic it self sorry for the long post thanks.

  11. Anthony

    Dog ate piece of hand burger meat seasoned with onion powder and garlic salt and has pieces of onion in it 😳😳😳 50 pound dog half a piece of a hand size burger patty

  12. Melissa

    My cat just drank water from a bowl in the sink that had a spatula in it that i used to make burgers with last night. We had used some seasoning on the burgers and the spatula was slathered in the juice and leftover seasoning. Cat is 13lbs. I have no idea how much he drank. Couldn’t have been too much though.

  13. Elizabeth

    I opened a pouch of tuna salad and when i ripped it open a little piece fell on my counter and my cat ate it. I then realized that the tuna salad contains pieces of onion. Now i don’t know if the piece my cat ate was tuna or onion. It was smaller than the tip of my pinky. If it were onion she had ate that wouldn’t be enough to worry about, right???

  14. That small of an amount shouldn’t pose a danger.

  15. Ann

    Thank you so much for your helpful posts. While eating a bowl of Progresso chicken soup, I managed to tip the bowl and a small amount spilled on the floor (less than a tablespoon) and my lightening speed 4 month old puppy got a lick of it before I could stop her. The ingredients on the back of the can lists onion powder as the sixth ingredient. My concern is that onion powder can be stronger in its condensed form. She weighs about 22 pounds. Thank you once again.

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