Thanks to all of you for your responses. It looks like less than 20% actually favored shooting the dog. I obviously agreed with the other 80%, as judged by my actions.
Sheriffoconee got it absolutely correct, it was not a warning shot. I fired into my rain soaked lawn and knew exactly where the bullet would be found. I was positive, before I pulled the trigger, that the muzzle flash and muzzle blast would drive the dog away. This was a situation involving an animal, not a human. Comments about confrontations with humans have no relevance to the subject of this thread.
Part of the problem is I am not at all afraid of dogs. I have confronted other dogs and been bitten occasionally, but always felt I controlled the situation. I felt that if I did not drive the dog away I would be bitten, possibly severely. It never occurred to me to get back in the car. I was simply going into the house. Had I not had the gun on me I would have pulled out my tactical folder, planning to use it if necessary. I do not retreat in fear when faced with a single dog. I do not carry pepper spray or other non-lethal human or critter repellents. Why should I? I have my gun.
I was not in the park, out for a walk, or in any other public venue. I was in my own driveway. Even in my normally quiet neighborhood, virtually no one is out walking or walking their dogs at 9:00 p.m. (1.5-2 hours after dark). Add to that the fact that I live on what is essentially a dead end street. I believe my actions were entirely safe for myself, my neighbors and, ironically, the dog. As well as effective in ending the confrontation.
I guess I could get one of those aerosol air horns people take to football games, it would probably work too. The simple truth is I chose to use my gun as a noise maker rather than a lethal weapon. The situation did not require lethal or non-lethal force, only a loud noise & bright flash. Hmmmm, when is a gun not a gun?
BTW It is a Federal crime to use wasp spray for any of the uses mentioned in this thread.