So we have this wild garter snake who usually lives in my raspberry bed, we have named him tails. Because in years past he has lost his tail and has a nub now.

Tails last week got injured by a dog, normally I would just let nature take its course, but the keeps ending up out in the yard and I've almost stepped on him. I have returned him to the raspberries several times, but I have noticed that he isn't moving the back half of his body past his injury. He seems to be dragging it. Though he moves behind his injury VERY VERY slowly away if you touch him. In front of his injury he is very active moving his head and tongue even striking at you if you get too close.

afraid that he's going to get injured again I have moved them into a tank in the house in a quite corner, until he recovers, and moves more quickly. I would like to get him back to protecting my raspberries ASAP.
We have water and a reptile heat rock in his tank. Is there anything else I can do to help him? Without taking him to a vet. And should I try to feed him crickets, or something else? Or I hate to ask it but, does this not seem like somethin he can recover from? Any advice in helping tails to recovery would be appreciated! Thanks!