Just after I got Deni (March this year) I had left to run errands for a little over an hour and my other furkids managed to dig into my husband's "war bag" (a gym bag that has supplies for simulated war exercises...USAF) which had an open MRE (Meals Ready to Eat...modern day K-rations) that had a snack pack of milk chocolate M & M's. Between the three of them (luckily tiny Deni was in her ex-pen) they opened the package and ate the whole thing, the only thing left was shredded wrapper spread across the living room floor. I quickly called the vet at 9pm and told her the situation and she said that everyone should be OK except for an upset tummy and yes, some diarrhea. She said to keep a good eye on Ally as she was just about 3# at the time. Luckily, no one had ANY symptoms. The vet said that since they had gotten into milk chocolate, it shouldn't be much of a problem because of the relatively low concentration of cocoa. However, if they had gotten into dark or baking chocolate (the worst) there could have been some reprecutions (sp?) because of the high cocoa content.
A few weeks later they got into another chocolate candy bar...I think it was half of a Baby Ruth that I had left on the living room table. No hurried call to the vet, I just kept an eye on all of them since I didn't know if it was the older Pekapoo or all three of the older furkids that got into it. Now chocolate is not allowed in the living room and my husband has to keep his war bag in a closed room away from the furkids.