There is some concern. The French bulldog in the packaging looks pretty dopie. They are usually handsome little fellows, but this one appears a bit drugged out - even his tongue ripples! So far Henry appears undamaged. Quiet and confused - but tongue isn't rippled.
The instructions suggest leaving it on no more than 12 hours out of 24. I took it off, and we went out to say hello to Henry's arch enemy, Sheldon the pit bull next door. Henry's barker obviously still works. As soon as he discovered that repercussion free barking was in place, he went wild. If Sheldon ever makes it through that fence, he is going to eat Henry. I tried to explain "low profile" but Henry didn't get it. Next time out, the collar is on.