What constitutes a normal dog?
How about one that isn't capable of this:
The Enduring Agony Of A Pit Bull Attack This happened two communities away from me, and it happened only a year and a half ago - so it ain't like I'm stretching for an example here. And don't give me the "media hates pit bulls" excuse on this one either. Had it been a person wandering a neighborhood causing this kind of destruction to man, woman and child it would have made national headlines.
If you want about a dozen more examples of what a normal dog ISN'T, do your own homework and use the search words "pit bull" and "malevolence" to find the thread where we've been documenting local instances of attacks. It's 7 pages long.