You should go ahead and call Animal Patrol. I mean if it has been weeks since the poor doggy has been running around town. And, it doesn't sound like he's feeding it if it came on your front porch and ripped open a bag of dog food. If you think that the owner will be mad, just tell the animal officers not to give him a name if he asks. I think that it would be the right thing to do. That is only my opinion though. I think that whatever you decide to do will be the right thing to do.