Ok, we got a rescue dog (part beagle/part brittany spaniel) three months ago. She has separation anxiety, and everytime I leave the room she starts barking incessantly. My friends think the dog is a nusience...and she is. We've tried shaking cans with coins, and also spraying her in the face with a water/whilte vinegar solution, which help somewhat, but even I am loosing patience.
Yesterday I got the citronella collar - and she immediately stopped barking after the first spray. I understand that beagles are stubborn, so I was impressed and thought, "Why didn't we do this sooner????"
I would stay away from wireless shocker collars.
10 years ago, with my last dog, I got the barker breaker collar and within 3 days the dogs entire mouth was swollen. When I took off it's collar I found that the prongs had made holes in his neck where blood and pus were draining out. It was unbelieveable. Took him to the ER right away and was told by the VET that he sees this "all the time with invisible fences/shock collars". He said that any wireless electronic device can make the collar zap the dog - your microwave, your phone, etc. THREE DAYS!!!! I could have killed the poor thing. Needless to say I never recommend that.
Every dog is different, and you never know what your dog will respond to. TRy the citronella collars and see what happens. IT's worth a try - and cheaper, too!!! GOOD LUCK!