that was really interesting. reminds me of the book "If Dogs Could Talk" (bad name for a book, but really good book)
http://www.amazon.com/If-Dogs-Could-Talk-Exploring/dp/0865476861
If it's commercially made chocolate, they'd have to eat a lot to get sick. If it's 'real' chocolate, a little amount can be sufficient to really make them sick. Commercial chocolate is a lot of fake stuff.
Those pics are great. They all look so humiliated! I love the bunny one though. That dog reminds me of the kid from "A Christmas Story". They both look like they have about the same feeling about their bunny outfit!