Feral dogs in packs hunt a lot like wolves...but I don't think feral dog packs encountering a person attack them because they think they're prey (unless you're gimp or a child). If the pack thinks you're a threat to their hierarchy of dominance, the alpha is going to try and take you down before you take him down. Most agression in canines come from a lack of dominance or a lack of structured dominance. If you show the dog who's boss with authority...then you're the boss. This is a common technique for making even the smallest dogs behave in your home. You make yourself the alpha and the dog behaves because you're the boss.

There was an interesting program a while ago (I think it was on Nova) about what would happen if people just dissappeared one day and they speculated that any dog that could get out of it's house, and was big enough to hunt (and not be killed by the bigger dominant dogs) would become feral and group themselves into packs regardless of breed in a very rapid amount of time. I find it fascinating how dogs can do this even if they're not raised in the wild. It's the same when dogs get picked up in packs of Coyotes. Half breed Coyotes can be really dangerous.

Now dogs which have been trained to fight or guard or have been raised a certain way might not work that way, I'm not sure. I do know that a dog raised in a normal home all it's life can turn into a savage predator in a fairly short period of time when it's surroundings change like going feral or being mistreated so who knows.

That's all good but I think the advice about a dog not stopping once it's committed is bang on. I've heard stories of attacking dogs having to be killed before they'd leg go of an arm or a leg. I'd say be prepared for a worst case scenario. I was told once that if the dog is going to get you, feet it your arm so it won't bite you somewhere vital (like the groin or neck) then fight with everything you've got...even if that means killing.

Personally I wouldn't want things to get that far...especially if you're bugging out. Who needs a shredded up arm when you're not in a position to go to the hospital? That in mind I'd think the pepper spray would be the best deterent as long as you're prepared for a fight in case it doesn't work. Having the other hand on a big stick, big knife, or even a big rock wouldn't be a bad idea.