Holiday hazard 3: Plants
Holiday plants: Curious pets often nibble on holiday plants. Though most are fairly safe, some can be prove fatal, even with small ingestions.
Lilies: All flowers of the Lilium species, including Stargazer, Easter, Tiger, and other Asiatic lilies, are extremely poisonous to cats. (Lilies are not toxic to dogs, and only self-limiting vomiting is expected if a dog ingests them.) The ingestion of just one or two leaves or petals is enough to cause sudden kidney failure. Even the pollen from these flowers is toxic to cats. Signs of kidney failure due to lily ingestion include vomiting, reduced appetite, increased or decreased urination, and lethargy. Kidney failure will begin within a few days of a cat eating lilies and, if not treated, the cat often dies. Any cat ingesting even small pieces of a lily needs an immediate medical evaluation accompanied by intensive intravenous fluid therapy, blood work, and hospitalization.
In spite of their names, plants such as the Peace Lily, Lily of the Valley, and the Calla Lily are not true lilies. While they may cause other issues (like gastrointestinal distress, arrhythmias, etc.) for pets, they do not cause sudden kidney failure.
Poinsettias, holly, and mistletoe: Though traditionally thought of as quite toxic to pets, the potential for poisoning from poinsettias is overhyped. The milky sap of poinsettias contains irritating saponin-like (or detergent-like) properties. While exposure to the sap may cause irritation to the skin and mouth, along with vomiting and diarrhea, serious or fatal poisoning is highly unlikely.
American mistletoe is commonly used in the U.S. as a Christmastime decoration, and is less toxic than its European counterpart. Ingestion of mistletoe most commonly causes self-limiting vomiting and mild neurological depression. Rarely, diarrhea and hypotension (low blood pressure) may also occur.
Holly is also less toxic than previously touted. The most likely problem caused by ingesting holly is irritation to the gastrointestinal tract from the saponins (similar to poinsettias) and physical damage to the stomach and intestinal tract from the spiny points of the leaves. Though holly also contains methylxanthines (also found in chocolate and caffeine) and cyanogens, these chemicals rarely lead to poisoning from small ingestions of the plant. Additionally, large ingestions of holly may also cause a bowel obstruction because the leaves are difficult to digest.