I have two males one Chow and one St Bernard. They fight every time I go into the back yard. Would the sound of a stun gun stop this from happening?

I've read your homepage and the last story there was from a lady asking you if you ever did try using the stun gun for sound effect. I would like to know the answer to that Question on Dog Fights because I have a medium size male (supposedly chow and Akita mix not sure) that has started beating the heck out of my male St Bernard. They both were puppies growing up together and all was well until the last month. The medium dog keeps attacking the St Bernard every time I go out side to change the water or water the grass. As soon as I go back inside he stops. Sometimes I'll hear him start to growl at the St. Bernard when I'm inside but I'll say his name sharply and a 'no' and that so far has done the trick. But not when I go outside. I feel like I'm locked out of my own backyard for the sake of protecting the St Bernard. The St Bernard has fought back with him but he's so big he can't match the speed of the smaller dog and tires easily. It's so pathetic at this point because the St Bernard hides behind me when I do outside knowing I will protect him. The only thing I can think of is something like the stun gun because there are no men around to help me all day long. Right now, I take a broom and look the medium dog in the eyes making contact (he is very smart) and tell him to be nice (he knows what that means) and I keep the broom out in front of him blocking him from the St Bernard, so he can?t attack. Neither dog is neutered, do you think if I neuter the medium sized one that would help? The vet just said maybe. Please tell me if you tired the stun gun for the sound effect. I'm desperate. I don't want to get rid of this dog, he is wonderful except for this one think. HELP!

Sharon