if a shock collar is hurting the dog, it's up too high. I've tested these collars on myself on EVERY setting. It's sure surprising, more than anything. Like a static shock after you've rubbed your feet on carpet. If it hurts you, then DUH you need to turn it down at least one level for large dogs and several more for small ones. I'm pretty wimpy so if I thought it was painful, I would not use it either.
and spray collars spray citronella, not lemon juice.
i'm amazed so many people are against shock collars, but have no problem jamming dozens of metal prongs into their neck or wailing on the collar to choke their pooch. There do seem to be a lot of people more intent on electrocuting their pet than learning how to properly train it or use a shock collar safely.
the problem with the above posted method is that my cattle dog mix is too smart for that. You are rewarding him for barking. And he knows it. As he wants a treat, he'll continue to bark for hours, now that he knows barking = treat. I'd rather reward for never starting barking at all. The less attention he pays to the fence, passersby, etc, the more lavish the praise and treats. Once a dog is already used to barking incessantly, though, there is not much going to stop it.