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  • Writer's pictureCoastal Equine

5 Toxic Trees That Are Dangerous to Horses

Updated: Sep 8, 2019

Originally published on

Keep your horses away from these dangerous trees; it may just save their lives.

Most horse farms contain lots of trees; trees lining the driveways, trees bordering fields, even trees inside pastures. But what kinds of trees are they? And did you know that some of them can be dangerous to your horse's health?

Here are five trees that you should keep your horse away from at all costs.

Red Maple

The Tree Center

The red maple is one of the prettiest trees to look at in the fall, but that is when it poses the greatest risk to horses. When the red maple leaves are still alive on the tree, they are not poisonous, but as soon as they fall off and begin to wilt, they can be deadly.

The toxin in the leaves damages the horse's red blood cells, causing severe anemia and kidney disease. Affected horses can only be given supportive care, and have a poor prognosis.

Cherry Trees

The Tree Center

Cherry trees are toxic to horses due to the presence of cyanide-containing compounds. They are thought to be most toxic when stressed by drought or frost, and young, rapidly growing trees are believed to contain a higher level of dangerous compounds.

Both live and wilted leaves are toxic, as well as seed pits, and once ingested, they release hydrogen cyanide into the horse's bloodstream, which prevents cells from gathering oxygen.

Affected horses can be treated with chemicals to reverse or negate this affect, but they have to be found in time for the treatment to be successful.

Plum Trees

Like cherry trees, plum trees have the same affect on a horse's cells and require the same treatment.

Both can be found throughout most of the United States and identified by their beautiful flowers in the spring and their fruit in the summer months.



The acorns, buds, leaves, and blossoms of oak trees are toxic to all livestock, though poisoning by oak is more common in sheep and cattle than horses, as a horse needs to eat a large amount to become ill.

When digested, the tannins of the oak tree are converted into metabolites inside the horse's gastrointestinal tract, causing anything from colic, renal disease, and bloody diarrhea. Treatment includes maintaining hydration and protecting the horse's kidney function.

Black Walnut


The black walnut tree is different than the previous poisonous trees, as it is not thought to be poisonous when ingested, but when it comes in contact with the horse's feet, usually through the shavings used to bed a horse's stall. If shavings contain even 20% black walnut, within 10-12 hours horses will begin to show signs of laminitis, including shifting their weight, heat in the hoof, and a digital pulse.

If horses are removed from the bedding quickly after symptoms appear, they have a good chance of recovery. The toxicity of black walnut is still a bit of a mystery, so most horses owners choose to keep their horses away from these trees in general.

These are just a few of the most common trees that are poisonous to horses. It is a good start, but far from comprehensive; the black locust and box elder trees, and a whole host of other plants can pose health risks to your horse as well.

As a horse owner, it is important to be knowledgeable about these dangers and aware when it comes to your horse's environment. It could save your horse's life.

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