thank you all for the well wishes and support, it really helps!
we saw our boy today - the good news is he can stand, albeit not very well. we think his brain got jostled around in his skull upon impact, causing swelling, bruising, and damage. his left eye is bigger than his right eye. so if the left side is damaged, that would explain the problems with his right legs. they sort of fold over at the wrist (front), and his toes flip, so it's pad up pointed toward the back on his rear hind leg. he can walk, but 1/2 the time he catches the paw correctly, other half he doesn't. he wobbles, and even falls down. but he can move them, so they are not paralysed.
he's still at the vets, on agressive cortisol treatments. they are keeping him another night, and day, and he may be able to continue treatment at home tomorrow night, but we're playing it by ear right now. if he has any set backs, he may stay there for a bit. but as of now, it's slowly getting more positive. we really need all the swelling to be gone, and some healing to take place before we can make any assumptions.
he does know us, he scrambled to get to me, gave kisses, wiggled his bum (then fell down). he ate a whole bowl of food, drank water, and went outside to relieve himself. he's alert.. however, his beautiful prick ears are not a pair anymore. the right one is flopped. he has major bruising and a cut there too.
it's slow going at this point. thanks again for the thoughts and prayers!
ETA: it was a regular clip, like you see on the thousands of leashes in the stores. slide the metal part down, it opens up. it was a medium grade, for a 60lb dog.