Tell you what; one of my neighbours (Elizabeth...{name changed to protect the innocent!!!}) has a Jack Russell. Nice little dog. (Aren't they all?) BUT he would bark at just about ANYTHING, and in particular, the dogs whose garden backs onto his.
She bought a thing from the Betterwe*r catalogue, which goes on his collar and emits a puff of air or something when he barks. Well, I kid you not; in a very short time he cut down to a couple of 'woofs', and now he STILL only does a couple of woofs, even when he's not got it on.
Brilliant! If only more people would make the effort!!!!!