I have a TENS unit. I got a dog not too long after I got one, we got the dog from an animal shelter. He was a wild Leonberger mix that was found out in the desert, not domesticated by any stretch of the imagination. I had been working to domesticate him, but it was a slow process. So, I had my TENS unit on one day after some rigorous physical therapy and my dog came up and ripped it off of me and proceeded to eat the wiring harness while it was hot. It was the funniest thing to watch. I stopped him pretty quick, but I'll always have that image stuck in my head. Fast forward a couple of years and my dog is finally domesticated.