Finally the animal shelter occured to me. Nothing about volunteering on their web site, but they clearly have hundreds of dogs in need of walking and cats in need of petting. Plus a full-time staff of vetrinarians, certified animal care workers, and a landscaper. You'll notice too this shelter probably looks way better than your last hotel in Europe, and each dog has his or her own mini-chalet-style quarters. This part of europe is great, the part where they are humane and never kill animals (well except medical research...) or prisoners.
Although the official opening hours are only 2pm to 5pm daily, I took a chance and stopped by. A semi-friendly worker, who had by the way the most incredible orange mask of fake-bake and whose cigarette smoke was blowing directly into the face of a rabbit caged barely 12 inches away, informed me that to walk dogs I would need to take a test at the City Vetrinary Office and become a certified dog walker.
Your dog is running free, and after calling several times doesn't come to you. What should you do?

Washingtonian living in Germany, which is really cute (except when it's not.)
I tend to get cranky very easily. And I'm a BIG complainer. Consider yourself warned.
Currently reading: The Information by Martin Amis
Just finished: Lolita by Vladimir Nabokov