Potter - I have a place called Millie Park for dogs near me - touted best in the country - (not by me - on their website)
the dogs even in the small breed area are almost ALL bigger than yorkies so it's really just a matter of judgement....
I agree WE need to convey messages when we're out - but it only takes one second for a yorkie to be laying on the ground or crying in pain.
we have to be extra careful no matter where we are.