Bad trees for horses

Horses don’t listen if you tell them to stay away from poisonous plants. But if you have plenty of good quality forage in your pasture, they’ll usually avoid them anyway. These aren’t just plants on the ground, horses have also been sickened while munching on certain trees.

Carey Williams is an equine extension specialist at Rutgers in New Jersey. She says the most common and most toxic tree for horses is the red maple.

"Especially if say, in a storm, a limb gets blown into the horses' pasture or the field, the leaves start to wilt. And the wilting process is actually what makes them toxic, but the other thing that makes them desirable to the horses is they also get loaded with sugar," explains Williams. "So, they are very sweet and horses don't know not to eat them until it's too late."

Other maple species are also toxic, just not to the same degree as the red maple, but   Williams advises keeping your horses away from all maples.

Keep cherry trees at a good distance, too, especially the black cherry. Also avoid oak, black walnut, and black locust. Make sure these trees are several feet away from the fence line, and take broken branches out of the pasture.  

Usually eating the leaves is what makes a horse sick, but in the case of black walnut, the shavings are a problem, too.

"If black walnut shavings gets into your horses bedding, and the horse stands on it – and they're not even quite sure of the mechanism – but only 20% black walnut in bedding can cause laminitis," she says. "So I always recommend if people are going to a sawmill to pick up their horse's bedding, they need to be 100% certain that there's no black walnut in there."

A horse that's eaten from a toxic tree may have digestive upset, depression, dizziness, and stumble around. If the horse just doesn't look right, call your veterinarian.