But one snap is a lead to further snaps.

If he's done it once the ability is there to do it again. Perhaps I'm obsessing over this but hes a big dog and he'll do a lot of damage if he ever wanted to, my overriding concern is that he is now getting the feel for wanting to.

As regards commands, well I feel that's something that gets practised daily. He's been able to sit with digestive biscuits on each paw without touching for 2-3minutes since he was 4 months old. Leave is something he's got hammered.

Why oh why do they do this, is really changes your perception and an animal you trusted I now can't and don't know if I ever will, which will affect my relationship with him.