In our case our neighbor let his GSP X breed with his lab X, repeatedly. I think at one point there were more than 20 dogs. I know for a fact that he couldn't feed them all, so they roamed the hills, killing cattle and deer on three ranges. The ranchers paid my husband a bounty for every dog he killed. We warned our neighbor, the old a-hole said shoot 'em all if you want. I shot at them one day when they were on our place. I phoned the rancher to come get his calf, or what was left of it. No ears or tail left and only one eye. It was hideous. The dogs did eventually all get shot or trapped. To this day I blame the neighbor, not the dogs. Luckily he left the valley.