The dog doesn't appear to be feral but if theres other dogs out there and the dog does appear to be walking a used road so maybe the dog is just walking back home or back to the owner. I have shot mangey looking ferals before and the one in this picture doesn't possees any charactertics in a feral dog. Its not the dogs fault but the owners in letting it run loose but I wouldn't shoot someones pet either. Have you tried animal control?

Bobby