I would love to see dogs be tamable. It would work like brahmim taming, except be harder. Much less chance to tame than a brahmin, so they will usually have to take a big bite out of you before you are able to tame them.
And, as above posts said, Outdoorsman would help tame it. Regular "Dogs" encounters will be easier (but not too easy) to tame, and "Wild Dogs" or "Wolves" encounters would be harder.
2000+ caps due to inflation-mechanic of Mercenary prices doesn't make any sense - it's a little dog.