When every other path has been followed and the dog is still not responding, a static shock to get their attention is not cruel, nor is it abuse. Continuous use would be.

The dog I used the collar on was a 10 year old stray that the shelter felt would never find a home. He was in poor shape when I got him and had a bad habit of jumping 6 foot fences. I finally got him healthy, housetrained, contained and accepting of people. I was his last hope and the neighbor next door was threatening his existence. This was a last ditch effort. And I don't feel guilty about using it in this instance. I have not needed it on the other three dogs I have had.

In a perfect world, the shock collar would never be necessary. Unfortunately I live in the real world. I've learned to be less judgmental as I've gotten older. And I never say "Never".