That doesn't help much, though. There's all kinds of things that are toxic to one species and not another, even just in Mammalia, and everything that anything anywhere ever eats is definitely not good for some other species.
The mechanism of toxicity (in dogs) is specifically relevant. There are multiple studies showing that artificial sweeteners in general are unhealty -- the body recognizes them -- and takes a variety of actions as a result.
Clearly these reactions in some cases may be simply performance related (see: http://www.gssiweb.org/Article/sse-118-carbohydrate-mouth-ri...). Whilst others can be catastrophic (see: xylitol in dogs).