Give her one teaspoon of household hydrogen peroxide, to make her vomit. If she hasn't vomited in 5 minutes, give her another teaspoonful. This was advice from my own vet just last week.
the sooner you do it, the better. After she has vomited, encourage her to drink...In about 30 minutes later, offer her a snack of something she likes, as this will slow down the absorption of the remaining chocolate.
A few M&Ms killed my pug, so this isn't to be taken lightly, in spite of what others say.
Here is the info from a veterinary first aid site> The first-aid treatment for chocolate poisoning involves removing it from the body, quickly, before too much time passes and the theobromine has circulated, damaging the gastrointestinal tract in the process. The treatment includes:
* inducing vomiting, which removes, and then administering
* activated charcoal slurry, which absorbs.
The sooner this is done, the less the effects of the poison. That, in itself, explains the importance of dog owners having an emergency kit in their homes plus the knowledge for quick first-aid treatment.
To induce vomiting, Michelle Bamberger in Help! The Quick Guide to First Aid for Your Dog, Howell Bookhouse, New York 1993, recommends using three percent hydrogen peroxide, one-to-two teaspoons by mouth every 15 minutes until vomiting occurs. Alternatively, she suggests using Syrup of Ipecac. Use, she says, two to three teaspoons, only once.
You can get Syrup of Ipecac at almost any pharmacy. You do not need a prescription from your doctor. Syrup of Ipecac is inexpensive and will keep for several years if stored at room temperature.
After vomiting, Bamberger says to give the dog by mouth activated charcoal mixed with water to a slurry consistency. The dosage is 1 teaspoon for dogs who are less than 25 pounds and 2 teaspoons for dogs weighing more than 25 pounds. << http://www.dogownersdigest.com/news/library/chocolate-poisoning-dog-care.shtml