Neighbours dog. It's alone while they are at work (they've just gone back) and it barks incessantly for hours. Apart from the noise being unpleasant it seems cruel to leave a dog for so long when it doesn't seem to like being alone. It rarely barks when they are home, except in the garden. I know nothing about dogs so thought I'd ask here. The neighbours are not on speaking terms and can't be approached due to an incident years ago.