You have probably heard it before, but unfortunately some have not...that chocolates and dogs don't mix. Spread the word. Why is it harmful? Chocolate is made with cocoa beans. Cocoa beans contain methylxanthine alkaloids in the form of theobromine and caffeinea and they are toxic to dogs. It is said that we, human beings, stop eating chocolates before we reach toxic levels, but dogs will go on consuming the stuff. Dark chocolates are the worse and white chocolate is the least harmful. But, hey, just forget about it!
There is talk about the amount of chocolate consumed vis-a-vis the weight of the dog before the chocolate consumption becomes toxic, but I'd say it again---just forget about it. Just don't feed your dog chocolates. They are too fatty anyway. As for symptoms of chocolate poisoning, here they are: from vomiting, diarrhea to panting, excessive thirst, constant urination, hyperactivity, abnormal heart rhythm, tremors, and seizures. And, of course, the grand daddy of them all is death. Severe cases will be fatal. The smaller the dog, the lesser the amount of chocolate consumed for poisoning to occur.
If your dog accidentally ate chocolates, try to induce vomiting within the first two hours. I have always had difficulty with this particular advice. How do you induce a dog to vomit? I don't know. I'd say, ascertain the type of chocolate eaten and take the dog to the vet asap. pronto.