Losing a horse is heartbreaking and it’s especially so if all it would have taken is a little knowledge to prevent the loss. Losing a horse to tree poisoning is devastating, partially because we see trees as part of our horse’s natural surroundings.
Anything in your horse’s pastures is fair game for tasting. If there is plenty of other food, such as grass or hay available, your horse probably won’t touch any of the trees within its reach. But, if it gets bored or hungry, to satisfy its need to graze, your horse might try chewing on tree barks, branches, or leaves. Some horses love the taste of willow, staghorn sumac, and a few others. Others nibble out of habit or curiosity, rather than hunger or taste. But, what this all means, is that any tree that’s growing within a horse pasture should be safe to eat.
Generally, horse owners don’t plant trees in pastures for this reason. Saplings have a good chance of being aggressively pruned by horses--to the point where you’ll be left with nothing but a ragged stick. If you do plant trees, you’ll need to find a way to safely protect them, until they are large enough that they are no longer a tender snack. The protection needs to be safe for both horses and the tree. If you plan to plant for a windbreak, it’s probably best to plant the trees on the outside of your pasture fence, just beyond your horse’s reach. Of course, you'll want to plant trees that are safe if they are eventually eaten.
Many pastures included forested areas. These provide important shade and shelter from the wind and are a nice addition to a natural setting. But, you may want to check that there are no trees that are actually toxic to your horse. Toxic trees and shrubs in North America include:
- Apricot cherry, peach and plum trees
- Locusts, including honey and black
- Mountain Laurel
- Horse Chestnut
- Pines (when eaten in great quantity)
- Black Walnut
- Red Oak
- Swamp Maple
- Red Maple
- White Sumac
- Water Hemlock and Poison Hemlock
Ingesting the leaves or needles, wood or bark of these trees can be fatal. Chances are if your horse snatches a mouthful of red maple or oak leaves while trail riding, it won’t be harmed. Many of these trees, bushes or shrubs won’t be attractive to your horse. They probably don’t taste good, and if better food is available, the horse won’t touch them. But if your horse gets hungry or greedy, a stomach full of leaves or tender bark could spell trouble, however.
Because most of these toxic trees don’t taste very good, horses will leave them alone. But, during times of drought, when pasture grass is sparse, your horse might snack on the trees despite the unpleasant taste. In the springtime, emerging leaves may taste fresher to your horse than a dry hay bale. Storms can down branches, putting otherwise unattainable tempting leaves within reach. And, in the autumn leaves on the ground may be attractive to some horses. Sometimes it’s simply not practical to cut all the trees down that may be toxic. Instead, be vigilant for opportunities or situations that might lead to your horse ingesting any part of a toxic tree.
If you suspect your horse has eaten parts of a toxic tree, call your veterinarian. Prompt veterinary treatment may be required.
If you do wish to plant trees for shade or windbreak in or near your pasture, you might consider the following:
- Tulip Poplars
- Carolina or Canadian Hemlock (not water hemlock which is toxic)
- Staghorn Sumac (shrub)
Even though these trees are safe, a horse can still overeat bark, twigs or leaves, which can lead to colic. If you notice your horse is sampling the greenery, be sure it isn't gorging itself.