Heh, wow, that is one heck of a first post. Interesting concept for a story, though. I'm a big fan of werewolf movies, but I don't remember many of them featuring dogs as being used to do anything other than hunt down werewolves. Dobermans are big and strong enough to do what you mentioned, and they're very loyal to their owners, but they're also already seen by society as potentially dangerous dogs.
So as far as our breed's image goes, a Doberman that runs down, attacks, kills, and then eats people fits right into the public's image of Dobes as vicious dogs. Dobes were used in Resident Evil as mutant killer dogs and in the movie "Hugo" to scare the daylights out of a child. It probably won't help the breed's image to be shown in the way you're talking about for your book.
As far as the alpha thing goes, some of the original studies on that were done in captive wolf populations. Animals in captivity behave differently than their wild counterparts. David Mech, the same guy who did the original wolf studies 40 plus years ago, has some new information out about how wolf packs function, and it's pretty different from the original alpha/subordinate theories. His site's here
, if you want to check it out.
I don't know about health. Probably not too many health problems, because as gross as it sounds, a dog that can eat a week old dead squirrel (thank you, Griffin) and not get sick, should be able to handle a fresh kill. Hah, just writing that about a human eating dog is gross.
Behavior-wise, I don't know. Dogs do have a pack mentality, even if the whole alpha/subordinate relationship might be a bit different from what the old studies tell us. A pack of dogs is more dangerous than a dog by itself. So, maybe it'd be natural for a dog to hunt in a pack and not have any serious behavioral issues from it? Hounds are bred to do just that, and most of them are pretty nice dogs around people. Good luck with the book!