What should I do about this fox?

A family of fox have been visiting my woods almost every night for about a year. They eat the mice, and squirrels I pull out of my barn as well as the occasional turkey carcass or meat scraps I throw out. I have a trail camera set-up that takes videos and still shots during their visits. They are such beautiful and clever animals plus they help me clean up.
About a month ago one of them had an unusual shaped tail that was necked down in the middle. I had not seen him for a while, but recently, he showed up with a totally hairless tail. I did some searching and the advice is generally: take it to a vet to see if it is mange, or shoot it and bury the carcass after letting it freeze.
I can’t do the first as this is a wild animal and I risk spreading the disease to myself, plus, the cost of a vet visit and treatments is very high. I can easily do the second as I have the equipment and experience and have no trouble shooting pests. But this fox is so beautiful, and when viewed at 75 yards through my 9x rifle scope I can clearly see the expression on his face and just can’t pull the trigger. Except for the bald tail he looks perfectly healthy.

So, Collective… is there a food additive or pill I can give him? Will he ever get better or will he die a horrible death if I ignore it? Or should I just grow a pair and shoot him?