With many kids, dogs and kitties and now Grandbaby around through the years, here's what I have done:
First, I have been known to get a shorter tree and put it up on a short dresser or cabinet. Then, soft and unbreakable ornaments are tied on to the bottom branches with yarn so that if they DO come off, they won't have metal hookies on them. We'll be there again this year with 8 month-old Little Miss Busy pulling up on furniture and chewing on everything in sight!