I had a chocolate labrador that literally wouldn't shut up. Since I found http://OnlineDogTraining.enle.info/?9TT1

She was 4 years old, we had our son and her barking was keeping him up at night. So my grandfather told me take a soda can put some change in it and tape the lid shut (I used duct-tape). Every time she barked I would shake the can and say quiet in a stearn voice. The sound startled her into stop barking then she heard my command. It took about a week and she stopped. You must not allow the dog to bark at all though. If you do then they will do it when they are not supposed to ie, when your not home. As far as for when your not home, I think the only none electrical, spray thing I can think of is a soft mussel. They can drink with the soft mussel on and it doesn't hurt them, they just can't bark or bite. From what I understand it is very hard to get a dog to stop barking at an advanced age. You are trying to stop something that is ingrained in them to do. Now a few questions for you, are the dogs being crate trained? If they are crated trying put a light blanket over the crate, to limit the stimuli around them. Do they have access to windows? What is the reason they are barking? Maybe it is something in there surroundings causing them to bark. Maybe people talking, people walking by, animals outside. If this is the case then maybe try limiting there access to this stimuli. Maybe crating them in a secluded area of the house to limit stimuli. Make it so they cannot see out the window any more. If it is seperation anxiety, take an old t-shirt sleep in for a night and then put it in the dogs crate with him. It will smell like you and help the dog feel more at ease. I did this when I went away to the hospital to have our son. It helped Kaylea alot.These are all thing my grandfather suggested to me for my dog. I tried them all but the crate training as I don't really believe in it. Reducing the stimuli greatly reduced her barking. The only thing that stopped it was the "noise can" I called it