This is the 2nd time I have tried this product (out of desperation). The first time I tried it with my two pug-mixed dogs it worked the first day (with one) and then not again after. I thought maybe something was wrong with the unit, so I took it back. Got another unit and am trying again now. Same story. The first day one of my dogs seemed to bark a bit less, but after that, both dogs just ignore it. This morning they literally woke us up barking -- it's like it's not even there. Back to the store it goes. Again. I need to find something else. :(