I would have to take him home with me....my two are a rowdy bunch at times, but would love another mate to play with I am sure.
A good idea to maybe try to find the owners, and explain how that their little dog nearly gave you heart failure, even if he was only takin a nap on the side of the road...and you are worried he might be hurt for real one day.....that might make you feel better...should anything really bad happen..good luck