Monday, December 3, 2012

Monday Medical Holiday Toxins: Mistletoe

Mistletoe in a hackberry tree on my sister's land in Texas
About this time last year I was in a van, driving through west Texas back country with a camera crew.  Suddenly, I saw something very familiar to me. Since we were on our way to film a Christmas special, it seemed all too appropriate.

"Look! Mistletoe!" I pointed out the window of the van.
No one believed me.

But having grown up with the stuff dripping from the oak trees on my parents' land in central Texas, I knew what I was talking about. It was mistletoe, and I won the Trivia round that day with the crew.

Oddly for a wintertime holiday plant, a large number of mistletoe varieties are tropical or sub-tropical. Mistletoe is also a partial parasite, and it grows in clumps in trees like oak, walnut and hackberry.

And since mistletoe is a known toxin to both humans and pets, it makes a good Medical Monday topic for December.

One of the earliest mentions of mistletoe is in Greek mythology around the first century BCE, in Virgil's The Aeneid. It also makes an appearance in thirteenth century Norse mythology. Mistletoe didn't really become a part of Christmas tradition until the 18th century.

1900's postcard, public domain
Back in the first century, mistletoe was actually considered to be an antidote to poisons. That's sadly ironic, since mistletoe is toxic to humans and pets alike.

It was also considered to be a cure for infertility in animals. Pliny the Elder documented a Celtic ritual in his "Natural History" series where mistletoe was mixed in a drink and served to animals to increase fertility. One wonders how many farm animals survived this practice.

There are two main species of mistletoe, the European variety and the American variety. The European variety is considered the more poisonous of the two. Both varieties are harvested commercially for Christmas decorations.

If you suspect your pet may have turned your d├ęcor into a menu item, look for symptoms to begin to show up in 2 to 24 hours. As with all toxins, the symptoms may vary with the amount ingested.

If you think it was just a berry or two that got eaten, or maybe a few leaves nibbled on, then look for things that might indicate you have inflammation in the stomach or intestines – stuff like drooling, abdominal pain, diarrhea and vomiting.

If your mistletoe is completely gone and you suspect Fido might have chowed down on it, that’s a bit more dangerous. In large doses, mistletoe can affect the cardiovascular system – especially if it’s of the Eurpopean variety.

You risk low blood pressure, abnormal heart rate, seizures, or a condition known as ataxia (or “walking drunk”). This can even be fatal, so seek medical help immediately.

And remember, if you ever suspect your pet may have eaten something he shouldn’t, call your veterinarian immediately. There is also a Global Crisis Solution Center that has a poison emergency page that includes animals. On it you can find a link to Poison Control Center phone lines in over 70 countries.

Wishing you a safe and enjoyable holiday season - for you and your pets!

Images of American & Eurpoean Mistletoe
Mistletoe species are partial parasites
If your pets eat mistletoe, what should you expect?
Pet Poison Helpline
Mistletoe commentary by Pliny the Elder


  1. We don't have that stuff, but we will be careful of it if we ever see it! Thanks.

  2. Very informative. That postcard looks like holly. The peeps, neighbor used to have a holly tree. We've never had mistletoe here so I don't have to worry.

    1. You're right! The mistletoe is behind the holly. (Both are considered toxic to pets).

  3. Are mistletoe and holly one and the same thing? Because the postcard drawing looks like holly. We do have holly here in vases during the Christmas season...

    the critters in the cottage xo

    1. Actually, they're different. In the antique postcard above, the mistletoe can be seen behind the holly. It's the brownish plant with the white berries.

      Is Holly poisonous? Mildly so, yes. Here's what the Pet Poison Helpline says about it:

      "Varieties of English, Japanese, and Chinese Holly contain toxic saponins.
      When Christmas or English holly is ingested, it can result in severe gastrointestinal upset (e.g., vomiting, diarrhea) thanks to the spiny leaves and the potentially toxic substances (including saponins, methylxanthines, and cyanogens).

      If ingested, most pets lip smack, drool, and head shake excessively due to the mechanical injury from the spiny leaves."

      Thanks for pointing that out!

  4. Well done we all need to think about these things. I knew lilies are dangerous for cats but never thought about other plants. Have a marvelous Monday.
    Best wishes Molly

  5. Thanks for the important information we did not know about.

  6. I suppose we should be happy we can't get mistletoe here...well, except the fake ones during Christmas. I can just imagine Tutu getting herself into trouble.

  7. We have a lot of mistletoe (and a lot of oak trees, and apple trees) around where we live in France. But it;s usually high up and out of reach.

  8. Thanks for all the information and links! And I know mistletoe grows in the southern US, but I've never known anyone who had it in their yard.

  9. My human's boyfriend once brought home some mistletoe. Well, it did not get the expected reaction because my human refused to put it up! She was afraid parts would fall off and we would eat them. We only get fake mistletoe here now!

  10. Thank you for this timely post. We don't do mistletoe in our house but it's good to know in case anyone we know does. Purrrrrrrrrrrrrrs.

  11. Very interesting! I didn't know anything about mistletoe, other than it comes in a little plastic bag at the grocery store checkout! HA! Pretty impressed you were able to spot it "in the wild!"

    We'll make sure no one gets any mistletoe snacks.
    ; )

  12. Thank YOU for this information! Mom knows about this but not everyone does. Our mistletoe is plastic and tastes like...well, plastic. Purrs...from your pals at

  13. Excellent post and great information!

  14. Awesome advice. Mistletoe is everywhere in Texas and I seem to notice it all year round.

    1. It is! At least between Georgetown and Round Rock it was dripping off the oak & hackberries. Mommy still remembers when someone pointed the stuff out to here - she was in high school and went, "reeeeally?!?!" when she saw it. It had been in her own yard, probably for years!

  15. Thanks for this information,
    we don't have this at my country, but we hear a lot on the movie or TV,
    so happy to see the real photo.

  16. Excellent info! Also, a few years ago someone gave me paperwhites (narcissus) at Christmas time and when I googled I found those are not good for kitties either, so now I mostly just don't have live plants around inside unless I know FOR SURE they're not a problem!

  17. We knew mistletoe was toxic but never knew what it did, Thanks for all the really interesting info, this was a great post. We didn't know it grew in the USA or Texas, either.

  18. Great information. Mommy is very careful about which plants come into our house. Me has always been a nibbler and she got rid of a ton of house plant when me came to my forever home.


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