My sister has a dog that sounds just like Delta.

We rescued 40+ Sibes staked out in the desert by a very, shall we say, "unbalanced" gentleman. Some of these dogs were completely feral, especially a litter of nine month old pups that had spent their entire lives staked on a six foot chain in the middle of the desert, with no human contact whatsoever except a 50 pound bag of dog food throw to them and a water barrel filled once every week or two. Literally.

My sister kept three of these puppies. It took about a year for two of them to come around to semi-normal dog status. The third one never will. Five years later, she is still pretty much feral. She will come in the house finally, after about three years ... but only when no one is home but my sister, and she remains absolutely motionless.