I too agree with Trouble.
My first port of call would be to their front door. I would say I had passed their garden several times and seen their pup, and as they worked and were probably short of time would they like me to walk it for them. Being polite and friendly can often get you a long way. Just getting to know then might liberate the poor little pup.
If this didn't work then I would pester every authority until they were sick of the sight of me and somehing was done.
I wouldn't steal him, because really I am a cowardy custard

Hi Alex, seems we often think alike I'd best not say anymore 'cos i was reprimanded for saying what I would do in court recently

Actually this 'Weekend What would you do' question is uncomfortably close to reality 'cos of the little Rottie pup on the South coast in exactly this scenario

Agree totally with Trouble.

I would only add that I know my local warden very well and I know that they would be right on the case.

i would try to get to talk to them then ,kindly suggest with your busy lives ,its probably hard for you to walk the dog or take him to the park .i was wondering if you would let me ,take him for a walk . even if his life dosnt get better with them ,just maybe they will tell you to keep him ,these kind of people generally get fed up quickly with things

No, I wouldn't take someone else's dog.

I'm with you on this one.

i like your style!!