First of all let me confess that I don't have leopard yawning shots. But I do have lot of tiger yawn shots. Since the focus of the shot is the yawn, I would have liked to move slightly to the right so that the visibility of canines is better. Also the tongue would have been captured if you would have moved to the right. Greater depth of field would have also helped. Thanks for sharing.
It looks like the background has been painted with black or at least darkened and it doesn't reallly look that good, despite that detail, the shot looks very nice and powerfull!