Once given, walk your
dog around or gently shake the stomach area to mix the
peroxide with the stomach contents.
Vomiting should occur within 15 to 20 minutes. If no vomiting occurs, you can safely repeat the three percent hydrogen peroxide once more.
Chocolate is toxic for dogs. However, I have known dogs who ate chocolate with no bad effects to them at all! But best not to take the risk. Your dog will throw up, then a little while later, will feel perfectly OK, and probably hungry again.