That is heartbreaking, especially for the children, I will certainly be keeping an eye out for any stray dogs around our area having heard your story. Also, had I known you had bok boks, I would have sent you over some stale bread and vegetable scraps from time to time.
There used to be a small mixed breed dog from two streets away that used to walk around to our place, (with a few side tracks as dogs are wont to do), then crap on our front lawn and go home again. I tracked it,.. twice, and felt like doing the same on their front lawn..... but I didn't have it in me.

In those days I had an old worn out slug gun, and I used a small punch to punch out some small wads of thick leather which I then soaked in oil to give them a little weight, loaded them into the barrel of the gun and waited. Next morning at about 7:00am I was waiting in the bedroom with the window slightly raised and the fly screen off and along comes Scruffy, Yes, by this time he was so regular we had even given him a name. He never hesitated, straight down the drive and onto the lawn, I waited until he was squatting nicely and about to take up the strain,.... POP!,... right in the rump. He went about a foot straight up, and his feet were doing about 100 miles an hour when he finally hit the ground again,... we never saw him again, except at a distance.
What a pity I no longer gave the air gun,....