Trees Toxic to Horses

You’ve just moved to a new place and you can’t wait to turn your horses out into their new pasture. The grass looks great, the barn is ready, the fencing is secure, but there’s something else you might not have even considered–the trees. Did you know there are several varieties which are toxic to horses?

Now I will admit to being a bit of a ‘tree hugger’. (Ask my husband–I get upset when he cuts down any tree on our place), but when it comes to the safety of my horses, toxic trees have to go. I just don’t want to risk it.

Just a few years ago, I realized I had several persimmon trees in one of my pastures. The persimmon tree, itself, isn’t poisonous, but horses love the ripe fruits and tend to overeat when they fall to the ground each autumn. The sticky insides of the fruit can get trapped in the GI system and cause a blockage known as a phytobezoar which may require surgery and can even cause death. Needless to say, those persimmon trees had to go!



Aside from the persimmon tree, here are several other trees which are considered toxic to horses:


Black Walnut Tree

These trees aren’t extremely common, but their natural habitat is on the eastern half of the U.S. We often hear to avoid stall shavings made from black walnut, but having them in your pasture also isn’t a good idea (for obvious reasons). This tree is highly toxic to horses and causes acute laminitis.

oak tree




Red Maple Trees

This tree appears in the eastern U.S. and southeastern Canada.  The Red Maple is a beautiful tree, but its leaves can be toxic to horses. The live leaves on the tree will not hurt a horse, but when they fall to the ground in autumn and wilt (or if a branch falls during a storm), they can be deadly. Scientists have not specifically identified the toxin in the leaves, but they do know that once ingested, the toxin will destroy the horse’s red blood cells, which will lead to severe anemia and kidney disease.



Oak Trees

Found all throughout the U.S. and Canada, Oak trees can cause severe problems not just in horses, but all livestock. The acorns, buds, blossoms, and leaves contain toxic tannins which can cause colic and bloody diarrhea. Horses don’t typically eat acorns, but might if they had little else to eat.

oak tree


Cherry and Plum Trees

Growing in many parts of the U.S., cherry and plum trees are also poisonous to horses. The leaves, fruits, and seed pits of these trees contain a cyanide compound which changes in the horse’s stomach to hydrogen cyanide, causing acute respiratory distress. They are believed to be more toxic during drought or early growth periods, but I would never consider them safe around horses. Diagnosis of toxicity is often made by drawing blood, which will be bright red if they’ve ingested enough of these trees. If caught in time, horses can be treated for cyanide poisoning.

Note: there are many varieties of both cherry and plum trees–none are safe for horses.


Cherry tree


Plum tree

plum tree


Black Locust Tree

This hardy tree grows throughout most of the U.S. and Canada and the bark, seeds, and leaves contain a phytotoxin which is extremely toxic to horses. If a horse consumes parts of a Black Locust tree, colic and kidney failure, along with other symptoms may occur.

black locust tree


Horse Chestnut Tree

This one is a bit ironic because of the name, but don’t let it fool you, Horse Chestnut trees are toxic to horses. Found mostly in the eastern parts of the U.S. and Canada, it has also been introduced along the west coast as an ornamental tree. This tree is poisonous to horses when it’s growing. The young sprouts, leaves, and seeds can cause muscle twitching and weakness, digestive problems like colic, and in severe cases, coma.

horse chestnut tree


These are some of the more common trees which are toxic to horses, but by no means, is this a complete list. If you would like to research a certain plant or tree species to find whether not it’s toxic to horses, I recommend this page.





Sources and Further Reading

Which Trees are Toxic?

Black Locust Tree







Hi! My name is Casie Bazay. I'm a mom, a freelance writer, and a certified equine acupressure practitioner.

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8 Responses

  1. Susan says:

    This is a very valuable article for horse owners! It’s easy to look up and find what trees are not good for horses but my question always is, what trees ARE good for horses if you want to plant for shade?

  2. Cathy says:

    Great visual article. I would like to add that when horses have ample forage they don’t typically eat things that are harmful to them. When given a choice they will avoid anything toxic. This is not to say that you shouldn’t be cognizant of their environment but also don’t be over reactive and kill off all your trees. I lived in CA for a number of years and my pasture was full of lovely large oak trees. I never removed one and never had an issue. Here in MI I have a black locust right next to their pasture, again no issues. I feel ample hay and they have grazing in summer time so there is never an interest.

    • Casie says:

      Very true, Cathy. Horses in the wild don’t eat toxic things when they have plenty of food sources to pick from. But I’ve seen far too many bare-bones pastures with little to no hay out. These are the horses which might eat something toxic.

  3. Michelle says:

    Just wanted to say I also live in Northern California and moved to 12 acres 2 years ago and have a lot of large old oaks including several different varieties on my property. My horses munch on acorns for almost a month in the fall ( even though they have access to hay 24/7 and so far I have not had any problems. I read a lot of articles about how poisonous they are and also how so many people witness there horses eating acorns like crazy and have had no bad outcomes. Every neighbor around me also has horses and oak trees galore and I don’t hear of any problems so I’m very skeptical that they are harmful. This being said I did feed bentonite clay most of the month this last year just to make sure any toxins were hopefully being eliminated and passed out of the horse.

  4. Thrace says:

    I had always heard that it really was the hoof to shavings connection that was the issue with the Black Walnut trees…. that the trees themselves weren’t an issue unless you cut one down and had random shavings the horses would stand in. “Originally, the tree was thought to produce a toxin in the leaves, bark, and nuts. However, more recent research suggests that only the heartwood of the tree contains the toxin responsible for causing laminitis in horses…”

    • Casie says:

      Yes, this is true, but that particular article also goes on to say, “to be safe, horses should never be allowed direct access to these trees.” That’s why I included it in this list.

  5. Julie says:

    I feel this article is over reactive and doesn’t give the horse the good sense he was born with to know what forage is good for him or not. Also some things that are poisonous in large quantities are actually good in small quantities and horses will self medicate if they want to get rid of parasites for example.
    There is no need to go cutting down all your trees, just be observant.

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