Technically it is not about "walking" at all, but still is a brilliant way to solve your dilemma – how to be with your dog while riding a bike – because unlike obedient humans, dogs walk to their own rhythm.
I thought this was the ultimate (and only) way to enjoy cruise the city with your dog – but the above makeshift looks three times cooler (and three times less safe) than that.
Available from Amazon (totally safe: click-ad free couldn't create a proper associate link).
P.S. Found in the bike segment of Amazon.com: what exactly is this about? Better not knowing.