I won't tolerate it because sooner or later the pawing escalates to kicking or banging the wall while they're waiting to be fed.
I have to custom mix everyone's feed and do the bulk of that at the house but still, there is some waiting involved while I get each horse's (4 of them) feed pan ready. I also feed according to pecking order which immensely helps to promote good "table manners".
My Arab is the worst for pawing. He has been with me 20+ years and still will occasionally paw to see if he can get away with it.
By now, all I have to do is look at him and, in my most authoritative "mom voice" say "STREEEEETRRRRRR!! NO!!" and he does.
Back before that didn't work, he got his knees whapped as needed.
For whatever reason my 19+ TWH, who has been with me 17+ years has suddenly decided to paw. He is a pig headed horse, who, "no" to him means "why not!?" I am in knee-whapping stage with him but alas this morning, I yelled at him and stopped pawing, so mehbee he won't needt he riding crop to his knees anymore[

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I have about five hard and fast rules for the horses and if they don't listen, they are in trouble. Happily they are all so smart they have learned when I literally wheel around from the prep table, point my finger, give them "the look" and tell them they had better behave, they mostly stop what they're doing.
It's all part of manners and respect and each person has to decide what they want to tolerate.
The pawing probably will rear its ugly head from time to time just always be consistent with the type of discipline used so the horse clearly understands why it's going to the woodshed[

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