Why is it dangerous to pets?
Mistletoe (especially American mistletoe) contains viscumin and phoratoxin, which irritate the gut and can slow the heart. Berries are the most toxic part.
Holly contains saponins and methylxanthines; the spiny leaves also physically injure the mouth and gut. Both are common in December.
Why speed matters
Delaying care significantly worsens outcomes. Some signs appear hours or days later, so "looks fine right now" is not a reason to wait.
Symptoms of mistletoe poisoning
- Vomiting and diarrhoea, sometimes with blood
- Drooling, mouth pain, pawing at the face
- Abdominal pain, not eating
- Slow or irregular heart rate (mistletoe)
- Wobbliness, collapse or seizures in large ingestions
What to do right now
- Call your vet or a poison line and say which plant and how many berries or leaves.
- Rinse the mouth and check for cuts from holly spines.
- Do not induce vomiting if the mouth is injured or the pet is already vomiting.
- Use artificial decorations, or hang real ones well above a pet can reach.
If your pet shows any of the signs above, go to the nearest emergency vet now and call ahead.
Sources & further reading
- ASPCA Animal Poison Control — pet poison database & dosage references
- Pet Poison Helpline — toxicology triage guidelines
- Merck Veterinary Manual — toxicology monographs
- Vets Now (UK) — emergency toxicosis guidance