I realize this is a very old thread but I just wanted to point out that acorns or anything oak related (think leaf in and outside water bowl) are toxic to dogs for anyone stumbling across this info. I have had to train my acorn loving dogs (pigs lol) to leave it with acorns. That being said the onions listed above are a no no too.
I don't know that one can always trust lists one finds on the internet.
Years ago, we fed dogs garlic to ward off fleas and ticks, and then a couple years ago, stories popped up that garlic is toxic.
My dogs eat acorns - not as much as the goats, but still - and we have seen no adverse effects. The dogs also eat onion, not raw, of course, but if it's in the leftovers I mix into their kibble, they get onions. I've had dogs for most of my life (past 50 years) and I have not lost one dog to onion and acorn poisoning.
Have lost a few to old age, though.
Do you think it was the onions?