I personally would not use pepper spray for the reason above. Beamersmom suggest the ultrasonic repeller that I know works. They sell one on Ebay for about half the price called BarkRepellar. There is a thread in the training forum with all kinds of great reviews. Let me add~my sister has 2 Dobs and it works on them. They are not aggressive but their barking made my mom (who lives with them) crazy. So I bought on for her and she loves it. When she is home alone they barked at everything going past the house~including leaves, squirrels, kids on bikes you name it. Now she uses the "zapper" and it stops their barking immediately.
The really funny thing is that my sister has no idea that she has it or even uses it.
Here is the thread:
http://www.yorkietalk.com/forums/tra...-repeller.html
Here is the link to Ebay that I used:
Dog REPELLER BARK Trainer STOP BARKING! Dog Training! - eBay (item 360305759139 end time Oct-07-10 08:46:57 PDT)
Let me add this as well~it does work well for fence barkers and also when my little sweethearts when they get overly excited in the yard too.