We use pain to teach our pets: if a dog does something he shouldn't we give him a thwack on the nose (not too hard of course, but enough to let him know: "don't do that!")

In my over 30 years of adult experience caring for dogs, I can say with full confidence that rewarding the dog for doing the right thing is far more effective in producing an overall well behaved dog than is punishing for doing the wrong thing!

And I agree with the rest 100%.

All we need do is consider another species treating us as we treat other species and it should be evident that we're fucking up.