Earlier today my dog(who weighs 20 pounds or slightly less) ate a piece of pizza. That pizza had pepperoni, sausage, and onions as toppings. I know there’s probably some danger that could result from the dog eating the cheese and tomato sauce, but what I’m mainly concerned about is the onions. The amount of onions he ate is pretty small(roughly 5 pieces of onion which were each smaller than my smallest fingernail), but since I know onions are toxic for dogs, I’m still anxious. How bad does the situation sound to you? I’ll be watching him closely anyway, but I wanted to have an idea about what to expect. Thanks.
(By the way, no I don’t ever give the dog pizza on purpose. The dog got this piece because it fell on the floor.)
I can’t imagine that the amount of onions on a slice of pizza could possibly be dangerous, but you should call your vet just to confirm.
It’s almost certainly more dangerous for you than for the dog. The main effect of dogs eating onions is horrible flatulence.
He’ll be fine. Onion can be toxic, but it would have to be be a much larger amount to be a problem. Do expect possible diarrhea from the general dietary indiscretion or cheese, but he should be fine.
This was news to me, but seems to be a real thing.
Thanks to everybody for the helpful answers.:)I’ll definitely look out for any suspicious symptoms, but your answers did help ease my worries. The page that KneadToKnow linked to said that serious issues can result if a dog eats 600 grams of onions, and I don’t think my dog ate anywhere near that much. Thanks again.
I have serious doubts about the toxic onion thing. In large quantities I could see it happening, but I know of plenty of times that dogs have eaten small amounts of onions with no observable ill effects.
“600 grams” is pretty much meaningless without knowing how big the dog is (chihuahua or St. Bernard?). It’s better to look at “15 to 30 g/kg in dogs” from the linked article. At 20 pounds, your dog is 8 or 9 kg, so would need to eat around 120 grams of onion, or close to 4 ounces, to show any significant effect.
In other words, don’t worry about it but don’t do it again.
We often feed our dog pizza. I had no idea it was supposed to be dangerous.
Very true. If anyone with a similar problem reads this thread in the future, I’d also advise them to ignore the “600 grams” total except maybe as a ballpark estimate, since it is, as you said, really the dog’s weight that determines how much is dangerous.
We keep a bottle of hydrogen peroxide on hand just for situations where toxicity is a concern. Given orally with a syringe or turkey baster it causes emesis. Some things like petroleum products or caustic chemicals should not be expelled, but for others having it on hand is a potential life saver.
Are there onions on your pizza? If not, the main danger is a fat-ass dog. 
I only recently heard onions and garlic are toxic for dogs. Obviously I will no longer let my dogs eat them, but truthfully I’ve done so all my life, with many dogs, and never noticed any ill effects. No, not even gas (although it’s certainly possible they had gas afterwards and I didn’t connect the events). So, I think the OP’s dog will be just fine.
:eek: I should have thought that swallowing hydrogen peroxide is way worse than swallowing onions. Surely there must be something safer you could use as an emetic.
Nope. It’s the only thing veterinarians will recommend to people to try at home. Anywhere from a tablespoon to 1/4 cup depending on the size of the dog. It is not recommended to use with brachycephalic breeds, or with cats. If it doesn’t work, they have to come in and we use the big gun - apomorphine.
The warning on H2O2 is there because - it makes you puke.
Moved to IMHO. We prefer that real life situations involving medical/legal question go there rather than General Questions.
samclem, moderator
The one on the right got into rat poison a couple years ago. A horse had stepped on a plastic bait station, giving the dog access to the bait.
I walked into the barn and observed her wolfing it down. Some H202 and she puked it all back up. Then tried to eat the puke (not the brightest. neither of us). What coulda been a disaster was just messy.
If onions were as dangerous as suspected, our family canines would be dead several times over. I’d like a little more evidence than just a web site.
That web page is accurate. Depending on the size of the dog, an ounce or two can be a problem. A big dog may be fine unless it’s a whole onion. Something like an onion ring is usually fine for anything but a teacup whatever. 0.5% of body weight is a pretty good rule to use. For a 20 pound dog, that would be 1.6 ounces, or 45 grams.
It’s rare, but I have seen a couple of dogs need blood transfusions due to hemolytic anemia from onion ingestion. Most treatment doesn’t need to go that far, and if the toxicity is mild, they might get over it on their own while being what the owner might think is being tired and dumpy for a few days. I wouldn’t want to risk it, just like with raisins and grapes and chocolate, just don’t do it!
Forgive me if I don’t take your word for it without substantiation. Got a cite? A study? Something more than just your opinion, even if you are a veterinarian?