I respectfully disagree. That is not true that small dosages will not affect large dogs. I am not a vet but I have worked in a clinic for several years, and know you can not predict the reaction in dosage that your dog will have a reaction to chocolate, onions, grapes/raisins (another toxic food for dogs), etc.
I've seen toy dogs who ate an entire bag of chocolate and did okay and a big dog who only ate one piece and came minutes from dying from cardiac arrhythmias and seizures. Then I have seen a few die from food poisoning as certain foods will attack their red blood cells.
Why would anyone chance that or say it's okay to treat your dog to unhealthy and possible dangerous foods ...just don't do it often to lower your chances.