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Mistletoe
Phoradendron spp. or Viscum
Mistletoe (Phoradendron spp. and Viscum album) is a common holiday decoration that is moderately toxic to cats. American Mistletoe (Phoradendron) contains phoratoxins — toxic lectins that affect the cardiovascular and gastrointestinal systems. The white berries are the most concentrated part and may appeal to cats. European Mistletoe (Viscum) additionally contains viscotoxins with stronger cardiac effects.
Important Notes
Toxic compounds: phoratoxins (toxic lectins) in all parts; viscotoxins in European Mistletoe; berries most concentrated
Mechanism: lectins inhibit protein synthesis in cells; cardiovascular effects include bradycardia and hypotension
Symptoms: vomiting, diarrhea, drooling, abdominal pain, weakness, bradycardia, low blood pressure; severe ingestion may cause collapse
All parts are toxic — fresh plant, dried decorations, and even fallen berries on the floor
Keep mistletoe completely out of reach during the holiday season; contact your vet if ingestion is suspected
Potentially Toxic Parts
Leaf
Fruit
Possible Symptoms Reported in Cats
Slowed heart rate (bradycardia), low blood pressure (hypotension), and potential cardiovascular collapse
Cardiac · Within hours of ingesting a toxic dose
Gastrointestinal upset, including vomiting and diarrhea (which can be profuse)
Gastrointestinal · Within hours of ingestion
Difficulty breathing or rapid, labored breathing
Respiratory · Within hours of ingesting a toxic dose
Weakness, odd behavior, and dilated pupils
Gastrointestinal · Within hours of ingestion
Disclaimer: This summary was compiled from multiple sources and is for informational use only. It is not a diagnosis or treatment plan. Toxicity can vary based on the substance, amount, plant part, and individual cat. If you think your cat may have been exposed to a toxic substance, contact a veterinarian right away.