@Shamas mom I think probably Shamas is just barking as an instinctive reaction rather than the sort of deliberate bark to ask for something (which is the sort that can be replaced with a chin rest). And in that case I would go with Mag's suggestion to feed every time he barks as a reaction to next door's dog. You are not rewarding the barking (it's just like us squealing/ gasping when something happens to alarm us) but you are building link that says next-door-dog-bark = treats, so that eventually the bark is nothing to be alarmed about.
Sorry, I've been busy with work
Yes, it's strictly reactive. He;ll be minding his own business, and TIKO will bark at the top of his lungs...no matter where Shamas is, he wil stop what he is doing, and run back and forth across the house, barking. Tiko upsets him. Tiko is another rescue from an abusive situation- he's small and mighty and barks at everything, to scare it away from Bob, who is in a mobility chair. Since Shamas is also afraid if the chair...it's a combination that we keep away from. He can handle Bob alone, but Tiko is TOO MUCH!
and on the flip side, he IS being re-enforced, because when he barks, my youngest gives him attention, telling him to stop that, and be quiet..or trying to calm him. Because she's often in the other end of the house from the neighbour's kitchen, and didn't hear the high pitched bark that started the kerfuffle in the first place. She only saw Shamas go absolutely off his rocker with seemingly no trigger. the only thing with a higher distraction value than Tiko is a squeaker. I have to use a squeaker to break up a fence fight, if Tiko enters his yard while Shamas is out(Shamas paces the fence too much for me to simply walk up and take hold of him)The very first thing Tiko does is start barking when his door opens, and run towards us..but Bob can't stop him because he's in a chair