1) Don't put food on the tree - strung popcorn might be pretty tempting to a dog (and ingesting the string can cause intestinal distress), candy canes may contain xylitol, a sugar substitute, which is highly toxic to dogs and salt dough ornaments, which seem incredibly unappealing to us, could be irresistible to our 4-legged garbage scows and cause salt poisoning. Best to just avoid any and all food products when decorating your tree which also protects it from falling over should a dog (or cat) start climbing to reach that goodie. 

2) Avoid using metal hooks to hang ornaments - let's face it, some of those things look like tiny dog toys nicely displayed for your dog to pluck one off each day. You know your dog's Kryptonite (plush? wood? etc.) so avoid hanging those low within reach, but even with proper planning your pup may still develop a "taste" for something new. Loosing an ornament might not be the end of the world, but having your dog ingest the metal hook with which it was hung, could be. 

Our dog Gracie, even at the age of eleven years old, still likes to remove an ornament or two from the tree every year. She hasn't chewed them in years, she just takes them to her bed and sleeps with them until we find it and put it back on the tree. To be safe, and remove the risk, I replaced the hooks on all our ornaments with ribbons just in case!

3) Skip the tinsel - it was a staple of my childhood Christmas trees, but we haven't used it in years. What is tinsel anyway? It's shiny plastic, or metallic, strands that are meant to mimic the look of ice on the tree. Tinsel itself isn't toxic to pets, but it is dangerous to dogs and cats alike. It shimmers, shines and moves - all of which may be too much for your pet to ignore.

It starts out with play, maybe batting it with a paw, but it can then move to the mouth very quickly as it's normal for animals to explore things with their mouths. At this point it may head down the “wrong pipe” — causing them to choke and cough.  With luck, they are able to actually cough it up and out—eliminating the problem. For others, though, the tinsel is actually swallowed and travels into the intestinal tract.

Again, if you're lucky, you'll just be picking up some shiny poop in a couple of days. However, if the tinsel gets lodged anywhere along the way (i.e. under the tongue, balled up within the stomach, or entangled in the intestinal tract), it's going to require a trip to the veterinarian for those dreaded words "foreign body ingestion", which may require surgical removal and nobody wants that for Christmas.