Tim Bowen sheds some light on the origins and definition of the phrase to go to the dogs.
According to the Macmillan English Dictionary, if a place or an organization is going to the dogs, it is not as good as it was in the past. People often say things like “This country’s going to the dogs. Things aren’t like they were 30 years ago” or “This train service is going to the dogs. The trains are always late. The seats are uncomfortable and the fares are high”.
The origin of this expression is believed to be in ancient China where dogs, by tradition, were not permitted within the walls of cities. Consequently, stray dogs roamed the areas outside the city walls and lived off the rubbish thrown out of the city by its inhabitants. Criminals and social outcast were often expelled from cities and were sent to live among the rubbish – and the dogs. Such people were said to have gone to the dogs, both literally in that that was where they were now to be found, and metaphorically in the sense that their lives had taken a distinct turn for the worse.