This sort of thing seems to be very common. I don't have collars for my yorkies or my boston, they only wear harnesses when they go outside. My big dogs have collars of course but they aren't always wearing them either. Thankfully they aren't runners so i'm fairly secure in them going in our fenced in backyard without them.    
I'm very glad your little guy is ok, that has got to be very scary for him and you.        |