I'll offer my ¢, bear spray at range. Pre-emptively. Get the bugger before he decides he wants to attack. If its a pack, (in addition to praying and loading your pants ;)) try to determine the alpha and get it. If it doesn't want to attack, the others hopefully won't either. Hiking staff-as others suggetsed use as a spear. Any "swinging" attacks should be short arc, much akin to a stick check in hockey. (Not a slap shot or golf swing). For a firearm I would suggest a taurus judge in .410 caliber. I believe it is five shot revolver, might be six. Design is forgiving of exposure of the elements, has no safety to fumble when panicing/adrenalized. Load the first two chambers with .410 shot the remaining with .45 long colt. With the first two rounds you can dispatch snakes and have a better chance of hitting a charging dog, or hitting mutliple dogs at range. The .45 LC is a cowboy round, slightly underpowered compared to .45 acp, but more than enough to do the job IMHO. Consider getting two soccer shin guards and attaching then to your weak side forearm. Consider the placement, relative to the angle of attack. You want them top and bottom of the bite angle.
BobS, I have seen feral dog packs right here in Tampa, Florida. Had them pin some female employees in their cars. Yelling didn't bidge them. A can of dented peas to the ribs (while standing safely on the loading dock) eventually did.

-Bill Liptak