Pardon me if this is a stupid question, but, once a wolf attacks your dog, how are you going to prevent accidently shooting your dog instead of, or in addition to, the wolf? "last resort" to me implies that wolf and dog are already fighting. I would think a better tactic would be to use the gun to scare off the wolf. Wolves also tend to hunt in packs, so you may be dealing with more than one.

I also would think you have to be a pretty good shot with a sidearm to be effective. Hopefully you are. I know I am not! I have hunted, and am a fair shot when I sit in wait for game, but not practiced at self defense with a weapon.

I have no experience in this, but I would think there are plenty of locals who have alread dealt with this, who can give you more useful information then we backpackers. Your employer should be helping you with this.