What about this ?
' Batsman firmly strikes the ball for a certain 4 runs but just before ball reaches boundary rope an eager dog runs onto the field, lifts the ball and carries it over the boundary rope much to the embarrassment of it's owner who quickly returns said cricket ball to awaiting fielder, leashes up his dog and hurriedly goes about his way with said dog now on it's lead '
What is the correct protocol in keeping with the laws and spirit of the game the umpires should apply ?
For me it's 4 runs. For that moment, ie when the dog actually grabs the ball, he/she/it became the boundary. It's the same as having the balancing struts on a sight screen that would otherwise be inside the boundary. If the ball hits one of them at an extremity, and bounces back in to the field of play, it's four runs (six if it's a no bounce, direct hit). That's because the Law is explicit and says no part of a sight screen can be inside the boundary. Therefore, the boundary will run in front of the screen, even tracing it so that if the ball passes between the struts and goes close to the main part of the screen without going under it, it's not a boundary, just the runs actually taken.
Law 19, especially 1. (b) explains it all. There's also an article on the Lord's website about trees inside the boundary and that's here https://www.lords.org/mcc/laws-of-crick ... in-action/