Poisonous Christmas Plants 

Mistletoe and Holly
A couple of holiday plants, specifically Mistletoe and Holly, are considered to be moderately to severely toxic, and you should call your veterinarian or poison control center immediately for specific advice.

Poinsettia Plant The sap of Poinsettias is considered to be mildly toxic/irritating, and will probably cause nausea or vomiting, but not death. It is better to err on the side of caution, though, and keep pets away from this plant.

Lilies and Daffodils
Additionally, plant bulb kits featuring Amaryllis and other plants in the lily family, Narcissus and other plants in the daffodil family, are popular gift items at this time of year. Pet owners should be aware that these plants are very toxic for cats, and sometimes with severe symptoms of gastrointestinal signs, cardiac arrhythmias, kidney failure, convulsions and death. Daffodils are toxic to both dogs and cats, especially the bulbs.

Christmas Tree
Don't forget about the Christmas tree. Christmas trees are considered to be mildly toxic. The fir tree oils can irritating to the mouth and stomach, causing excessive drooling or vomiting. The tree needles are not easily digested either; possibly causing GI irritation, vomiting, gastrointestinal obstruction or puncture.