I too am a dog lover and hope to never have to shoot one in self defense. I was in LE for about 37yrs and never had to as well as delivering medical equipment for about 6.5 years. Only once did a little ankle biter come out and nip at my pants cuff. I personally think actual dog attacks are way over blown and that some seem to be just looking for the excuse.
Recently two pits had gotten loose from their yard and came up my street. They approached my wife, running while she had our elderly female lab with her on a leash. She was needless to say a little freaked out.
The two went up to her and our dog and then proceeded to go into our neighbors yard. He said that they tried to get into his chicken coop. I heard shots and the two came back toward my house. Both dogs came up to me. I could see that one was injured. I held the two while my wife called the police and our vet. We located the owner. Neither dog was vicious.
I can certainly see times when it is necessary to kill a vicious dog but I think that in many cases it is unwarranted.