The three squares that I ate could have been fatal to a ten pound dog. A sixty pound dog could easily eat the whole package of eight squares, cardboard and all, and that would be enough to be fatal. If I had eaten all of the semisweet and unsweetened chocolate in our cupboard, you would be reading my obituary now, instead of this column. An eight ounce cup of coffee contains about 100 to 300 mg of caffiene, and espresso contains about 100 mg of caffiene per ounce. A ten pound dog would have to drink two or three cups of coffee, or several ounces of espresso to risk a lethal overdose.
Dogs are more likely to get into candy bars and other treats, usually made from milk chocolate.
They contain considerably less caffeine and theobromine so fatalities from accidental chocolate poisoning are very uncommon. Chocoholic dogs usually don't eat a lethal dose, and they probably eat the wrappers and a lot of other junk with the chocolate, so they begin vomiting soon enough to get rid of most of the chocolate. But it is probably best to call your veterinarian. In most situations, the prudent thing to do is induce vomiting to empty the stomach before other symptoms appear. And supportive care may be needed.