maple leaves are toxic to horses

Maple leaves are toxic to horses!


This is a complicated situation, but the bottom line is that red maple leaves can kill a horse.


  • There are varying shades of unknowns when it comes to other types of maple trees, as well as how much your horse eats and if the leaves are green, wilted, or dried. Which, naturally, makes me consider all maple leaves at all stages of life from all types of maple trees a possible hazard. Better safe than sorry, right?


There’s at least one substance in maple leaves, gallic acid, that is dangerous.


  • Researchers believe there is more than one toxin, but this one seems to be the big one. When leaves are green and on the branches, the leaves are mostly water, thus diluting the amount of gallic acid.


  • As leaves wither and dry, the water disappears, and the concentration of gallic acid increases in the leaves. It is believed that concentrations of gallic acid also vary with the age of the tree, the climate, the type of maple, lots of different factors. All of which really can’t be predicted.


  • It does take a horse eating about one to two pounds of wilted or dried leaves to be affected by the poison. That seems like a lot of leaves considering they weigh as much as air, but have you ever known a horse to turn down a tasty snack in mass quantities?


red and yellow leaves on the ground



Signs your horse in is danger from the toxins do damage


  • Your horse will be sluggish, seem to have colic, and probably stop eating. You will also find dark and discolored gums, a rapid pulse, and almost black urine.


  • The toxins in maple leaves act on the red blood cells of your horse, causing them to fail to carry oxygen. The red blood cells may also break.


  • These events cause a chain reaction in your horse, that essentially clogs the kidneys and puts your horse into an anemic state.


  • Here’s the critical part – once symptoms develop, your horse’s chance of survival is decreased. If you catch your horse eating maple leaves, call the veterinarian even if he looks fine for the moment. There is no antidote or cure, so early intervention with supportive treatments like fluids is key.


If you have maple trees around your farm or barn, be sensible about raking leaves and keeping the paddocks and turnouts far away from any maple trees.


  • You will still find stray leaves, especially after storms and in the fall, so have a plan for dealing with that. Removal of the maple trees is an option, too. You might also talk with your veterinarian and factor in the type of maple – red maples being the typical and severe danger, with other species being risky to some degree.

How do you keep your horse from snacking on maple leaves?