I have a few small scars on my leg to attest to this. When I was a kid I had neighbors with a couple of Rottweilers. Was playing next door in their yard, and tickled one of the kids, he screamed and the male Rott clamped on my leg for just long enough to tell me to let go. Totally my fault, he was doing his job and protecting his charges. Left a couple of holes in my leg from his canines. He also adopted my little sis as one of theirs and would bark at my mom when she came out to tell (yell for) her to come in.
If you are having to "sell" your wife on getting dogs, don't do it unless you can sell her fully on including them as full members of the family, inside and outside of the house. IMO, many outside only dogs end up being neglected in the amount of attention they receive just because their owners get too busy. They are harder to ignore and become more involved in the family life inside the home where they can pester you for some lovin'. As mentioned earlier, dogs are pack animals and do not do well when separated from their pack/ pack leader.