Are you talking about one dog or a pack of dogs?

Also, feral dogs are very different than farm dogs, which are used to people and generally friendly. Feral dogs that are unafraid of people are the worst.

Can you be a little more specific about what you're imagining?

Loosely speaking, one dog is manageable. A pack of dogs is bad news. Run for your life and climb a tree, get in a car, etc. I don't know anyone who could control something like that. I honestly don't see how a firearm is going to help, unless you are far away and have a machine gun...