When my family had Gracie the Great Dane mix, we'd put a child's playpen up a distance around the Christmas tree for two reasons.

A - a Great Dane tail is a powerful thing, high up enough to knock off a LOT of ornaments, and not vert well connected to the brain or nerve centers - she, quite frankly, had have no idea her tail was whacking something, so it's not like we could train her NOT to wag near the tree.

B - we, like many, put Candy Canes on the tree - which happened to be the only "food" Gracie would literally drool over. She loooooved them, so to not risk the tree, it got put in a playpen and the candycane were put pretty high up.

Most of the presents were put there the last few days, the majority appearing Christmas night, so they didn't become a problem.