Milk Chocolate?

My daughter went out an left a good-size milk chocolate candy bar on her bed - it was about king-size but not sure how many ounces). When my daughter came home she found the wrapper chewed up on the floor and tell-tale chocolate smears on her new comforter. The only four-legger allowed in her room is Tally (who weighs twenty-five pounds). This was yesterday afternoon. Tally has shown no ill effects so far, and is acting perfectly normal. Should we continue to be concerned, or is she home free? It's been about eighteen hours. I've heard that milk chocolate may be less toxic than dark chocolate, and she has eated milk chocolate before (never given - always stolen) and was fine but she never ate this much before.