[WeedWacker]

Option pertaining to OP:
I'd almost rather have a knife on me. Not a folder but a fixed blade big BAMF piece of metal. Like my BK7, or my bushman which weights next to nothing. Personally, caliber doesn't seem that big a deal with pitbulls but bigger holes generally work better. A little .357 snubbie would be good. Won't have the jamming issue the PPK had in the story posted above. If you want the high capacity of an auto, I'd lean towards a .40 preferably or 9mm at minimum. Just expect that if you DO get attacked that they will be on you before your first shot so expect to be bit and mauled. With a snubby treat it as an extension of your hand and wield it like a sword, get it close before you unleash fury. Run drills where you face an angry dog and escalate to multiple dogs. Since you have the fence you will probably see them coming first and it takes a bit to get over that barrier.

Better option:
Maybe you should look into getting a wooden slat fence with slats made of 1x4's and about 5.5 to 6 feet high. If you make it where there isn't a gap between the boards the dogs can't see you and will not have as much incentive to act up nor iwll they be as intimidating.