Common Plants and Trees That Are Poisonous to Horses

by Ross Stockdale

Common Plants and Trees That Are Poisonous to Horses

There are hundreds of poisonous plants and trees that grow all throughout North America. Because many of them are quite common, it's important that horse owners learn to recognize which ones are local to their area and the common symptoms they cause when ingested by a horse. 

While some plants and trees can cause mild symptoms such as excessive salivation or drooling, consuming some extremely toxic varieties can lead to severe illness and even death. This risk is why regularly checking your horse's pasture, practicing pasture maintenance and providing plenty of forage is key to keeping your horse happy and healthy when they are turned out.

Plants and Trees That Are Toxic to Horses 

Whether your horse is turned out 24/7 or receives limited pasture time, there is a chance that they could come in contact with and consume some of these poisonous plants and trees.


Some common plants which are poisonous to horses include:

  • Alsike clover: Even though alsike clover is considered a low-toxicity plant, it can cause photosensitization, which is a painful blistering of unpigmented skin. It can also lead to liver disease, though this is not as common.
  • Buttercup: Buttercup is also considered a low-toxicity plant. Horses that consume the leaves or flowers could show symptoms such as excessive salivation, diarrhea and colic. 
  • Poison hemlock: Unsurprisingly, the aptly named poison hemlock is an extremely dangerous plant. All parts of this plant are toxic. Signs of poisoning include frequent urination, central nervous system issues such as incoordination and respiratory failure.
  • White and red clover: Toxicity from excessive clover consumption doesn't actually come from the clover itself. Rhizoctonia, the "black patch fungus" which grows on clover, produces the toxin slaframine. When horses consume this toxin, they'll exhibit "slobbers," or excessive salivation. 


North America also has several common trees that are poisonous to horses:

  • Black walnut: Certain parts of black walnut trees are moderately toxic, including the bark, nuts and roots. If black walnut is present in stall shavings or bedding, it could lead to edema, laminitis and colic. 
  • Red maple: Red maples are extremely toxic, with the most poisonous part being the wilted and dried leaves. Consuming just 1.5 pounds of these leaves can lead to symptoms ranging from dark urine and breathing difficulties to destroyed red blood cells and death.
  • Oaks: Oaks, including black, white, chestnut, red and pin species, are moderately toxic. This poisonous tree is at its most dangerous when it has new leaves and green acorns. Signs of toxicity can include poor appetite, increased drinking and urination, weight loss, diarrhea and edema. If consumed in excess, it can result in kidney failure and death. 

Find the Supplies You Need to Keep Your Horse Happy and Healthy at Horse Tack Co.

At Horse Tack Co., we have the horse health products you need to treat and diagnose various illnesses and injuries. From thermometers and stethoscopes to digestive aids and hoof care products, you'll find a wide range of products on our site. 

If you have any questions about our health products, be sure to give our knowledgeable team a call at 866-624-8225 or fill out our contact form and we will get back to you.     

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