That's really terrible! And doubly awful given the number of times we've tried to get people out to see about mistreated animals (like the dog a few doors down that is old and tatty and left to roam the streets all day long, pooing everywhere and at risk of being run down; or the many many many strays we've found over the years). The RSPCA always tell us it's the council's job and of course they don't do anything about anything.
In our old house we were always picking up strays and taking them to the police station. Luckily it was really close by and they had kennels for their dogs they could keep the strays in until they could be taken to a home.
You should put your puppy's poo through the neighbour's letterbox when no-one's around.
