We used the Nu-Skin on Gracie the Zoomer for a chunk she took out of her pad that was about 1/2 the size of a pencil eraser and about 1/8" deep - it didn't phase her at all. But...this was also the second day after she hurt it, so some initial healing had occurred by then...maybe that's why it didn't sting. It worked really well on her and didn't come off, but she wasn't out there herding, either, just zooming!
We put a new coat on every couple of days until it healed.
I've used it on me, and it DID sting like heck at first when put on a fresh wound.