Well, it makes sense. Let your dog gobble down a bunch of bread dough - or maybe you don't let him, he just does it - and he can get quite sick.
I knew this on some level; I just didn't know why. Seems once the dough has been eaten, it can rise to the point of causing an intestinal obstruction. Yikes!
The yeast creates another problem, in that it can ferment sugars and that's a whole separate mess because it can cause ethanol (yes, alcohol!) poisoning in an animal.
Seems what's not good for humans isn't good for animals either.