The general consensus is that the white, milky sap of the poinsettias can cause some gastrointestinal discomfort, but overall poinsettias are not poisonous to pets.
Here are some links to web sites for more information:
Also, in case you are wondering, poinsettias are not harmful to humans, adults or children.
So if you are looking to pull one over on Cousin Eddie this Christmas, you can whip him up a nice salad of romaine lettuce and poinsettia leaves with out fear of actually killing him.
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