Christmas trees are not toxic to dogs, but there are some things to keep in mind when having a Christmas tree with a dog around. Some species of Christmas trees, such as Douglas fir and Norway spruce, can cause stomach upset if eaten in large amounts. Additionally, the needles of some Christmas trees can become lodged in a dog's throat or stomach, so it's important to supervise your dog when he's around the tree. Finally, it's important to make sure that any decorations you put on the tree are safe for dogs to play with or chew on.