Viv :
I'm owned by only a single dog...so I'm not an expert, but I'll attempt a humble reply to your thread...
Mini Schnauzer's have many common traits of the breed and two of them are that they are VERY smart & VERY attached to their families.
As I understand it...M/S's get very upset when faced with the prospect of family members leaving "the safty of the pack"...because those loved ones are venturing off into the unknown "without" proper protection to insure their safety when they're away.
Perhaps if you can imagine a mother's joy at being re-united with a her soldier son after a tour of duty in Iraq...you can appreciate how your dog feels upon seeing you again after a day away.
To her, you're taking a horrible chance with your life that makes no sense at all & she's torn up with worry when you leave (& this is worse the more you do it) & she's tremendously relived when you return.
In our case, our fur-daughter used to jump up into our laps & stand over us with her two front feet on our chests, to let us know that she was re-claiming us & we should never do anything so foolish as to leave without her again.
Malibu still does this to some degree with Mary, but since I bring her to work with me every day, she's quite content with the fact that I (at least) have understood the message & so she's not left alone in the house any longer...she's along with me to insure my safety.
My secretary has become part of her extended family & she protects Christine's front desk from any threats too...& she also keeps the office building safe from the threat of Cats & Squirrels when we go out for short walks during the day...I suppose that she imagines this is done not only to "do her duty", but also to patrol the area.
Malibu is very used to the routine & is mellowing over time...she's three yrs & a few months at present & we could not have expected our lives to be so enriched by a dog.
I feel truly sorry for people who are never owned by a mini schnauzer.
We're much safer now !! 
