I cary a very small .22 for dog protection myself. I will ONLY load it with the rat shot loads and have ONLY ever fired it into the ground in front of a dog that I couldn't shout down. The number one reason I use the rat shot is that I want to be sure my shot stops rite where it hits! I am responsible for every bullet I fire, wether it hits an intended target or unintended target. (Sorry to say, I was bitten by a dog in April that I had used HALT on two times in the past. My mistake there was not calling the sherrif about the dog the first time. I will not be the brunt of another dog attack!)
As far a the darts, pellets, etc. Our best bet is to get as much information as possible and call the police!