>but why are grapes bad for them?
Not Maria,but grapes and particualrly raisins have been shown to cause renal failure.Some dogs have only eaten a handful and died,others have had serious kidney issues for the rest of their lives.Yet again other dogs can eat grapes their entire lives and not have any detrimental effects.My dogs and many others i know have had the odd grape or two over the years.I think it's up to the individual dog and how they metabolise them.
They're not exactly sure what exactly it is in grapes that causes the problems.
>I know that raw onion is not good for dogs
As far as i know cooked onions arent either?