Why not also: Was geben Sie diesem Hund?
It's also correct.
I also agree, it would be the formal approach
Would "Was gibst du diesem Hunde?" have been the correct sentence at some point in the last century or two?
Wieso nicht Was gibst du jenem Hund??
Possible but rare. Jener has practically vanished in spoken language, it's considered as elevated or literary.
Why not "Was gibst du dem Hund?" I thought "Was gibst du diesem Hund?" would mean "What are you giving to this dog?"
I have a hard time remembering the work