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.
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.
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.
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.
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.
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.
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