I was asked if live trees used for X-Mas are dangerous to dogs . I truly did not have an answer, so decided to do some research on that and here's what I learned:Trees in general are not dangerous but  there are many other dangers at this time of year.
Household plants we commomly have such as Poinsettas, Hibisus, Holly, Azaleas, Mistletoe, Lillys, Amaryllis, Christmas Cactus and Potpourri are the most common.
 Water in the tree stand can be harmful if you put fertilizer in it and if you put aspirin in the tree stand water it can be fatal to cats. 
Tinsel and garland are also dangerous to our pets.They can block there intestines.
Chocolate is also very dangerous to dogs. Just a couple of ounces can cause severe side effects in a small dog. They can not break down this treat like we do. 
One last thing I would like to mention is the melting salts used on the ground. Most of these salts can cause severe burns to the dogs pads!Either use a protective wax on your dogs pads or try booties.