How in the hell did you "had to shoot it. I was in his backyard."
I wondered about that, myself. If it'd been MY dog, I'da said, "Good boy!" Then I'd be asking you why you were in my back yard? You shoot my dog in my yard?
"jacob", if I read your original post right, the dog was not growling or barking, it was simply running towards you. Admittedly that's a scary scenario, but you don't really KNOW it was going to attack, do you? Did you know the dog? Was it a proven attacker? In the aftermath, is there a leash law where you were? If you truly believe the dog is dangerous, you should call the Humane Society or Animal Control in your location.
You negated the danger and no one got hurt. That's ALWAYS the bottom line in ANY gunfight, even with a dog.
If you're concerned about ricochets, maybe you should spend more time at the range...?