Aw, that's sad. The thought of a doggy being lost and looking for it's people just hurts my heart.
We have some friends that feel the need to take their dog with them nearly everywhere, even at the expense of others. He's a pretty well behaved dog but it has a lot of health problems and can be kind of gross sometimes. They don't like to leave him alone because they already feel bad about having to leave him for work. And they always imagine that he's at home with his little legs crossed because he has to pee.
My dogs, on the other hand, bark when they get excited. They don't go anywhere unless it's a place where their behavior is accepted and expected. Plus, I find that they are more comfortable at home. Yesterday, my husband didn't work. When I got home and had one dog on my lap napping, my husband said "he's all tuckered out from all the running around he did today," I said "really?" He said "no, silly, he hasn't done crap today except sleep."