Plant Toxicity

Common Plant Toxicity Concerns

By Dr. Karen Burgess

The belief that the poinsettia is toxic is somewhat of an urban legend as this common Christmas plant is actually fairly benign. The milky sap produced can cause oral irritation and mild stomach upset but these symptoms are typically self limiting and do not require veterinary intervention.

Toxic to pets and often found in holiday arrangements, holly contains methylxanthines similar to chocolate. The leaves are somewhat prickly which may discourage ingestion. Holly can be both irritating to the mouth and cause severe vomiting and diarrhea. Typically pets do not ingest enough of the plant to cause serious symptoms. Both Holly leaves and berries are toxic.

Unlike the poinsettia plant, mistletoe can cause significant symptoms in pets including GI upset, neurologic signs (lethargy, seizures, coma), and difficulty breathing. The amount of mistletoe that would cause toxic signs is not well understood. Fortunately, most pets do not ingest enough to cause serious consequences.

Sudden and severe kidney failure in cats is associated with ingestion of very small amounts (ex. couple of bites, exposure to pollen) of this extremely common plant. Vomiting is the most common initial symptom. This will often resolve initially. Within 1 to 3 days complete and irreversible kidney failure can develop. If treatment is started within 18 hours of ingestion (including hospitalization and aggressive fluid therapy for a minimum of 48 hours), prognosis may improve. Lilies are not toxic to dogs.

Tulip and Hyacinth bulb toxic components are concentrated in the bulb. Ingestion of bulbs can cause GI signs including anorexia, vomiting, and diarrhea. In more severe cases nervous system signs can develop.

Tomato plants (leaves, fruits, and roots) contain a chemical called solanine which acts to naturally protect plants from pests and fungus. Found in highest concentration in young or green fruit, solanine can cause a range of signs from gastrointestinal upset to more serious neurological signs. Fortunately absorption is poor orally and therefore intervention is rarely necessary. Potatoes also contain solanine and can cause similar signs.

Although containing potentially toxic pyrethrins, mums are considered minimally toxic in pets causing primarily gastrointestinal upset.