Let me see.. I think maine has a ban on keeping any species of garter snake. unfortunate. Bottom line is, there's probably billions of that same snake out there thriving and so very little sympathy from local authorities, although you do have our sympathy. We love garters and hate to see one die, no matter how insignificant the individual might be. Good luck. I hope he makes it. you really do need to keep him warm though, 75-85 I would say, for an injured garter, and for goodness sake, handle him as little as possible, and keep him in a sterile(as can be) container. The risk of infection is high, and the germs aren't good for humans either. Wash your hands!

I have often found very young garters out on the ground this time of year, around Portland, Oregon, even if it's very cold. Usually, it's because they tried to hibernate in active rodent burrows and were pushed out, or flooded out by high water. It's possible the injuries were caused by a rodent, and the dog just happened to find him.