It's concerning to think about chocolate and dogs since chocolate can be toxic to them. The danger mainly comes from the theobromine in chocolate, which dogs can't metabolize well. The amount that can be harmful depends on the dog's size and the type of chocolate. Dark chocolate is more toxic than milk chocolate. Do you have a specific situation you're worried about with your dog? If you suspect your dog has eaten chocolate, contacting a vet is the best course of action.