In autumn, as trees transform into vibrant colours, they create picturesque scenes. However, this season also brings potential risks for horses. Deciduous trees and shrubs shed their leaves and seeds, and strong winds or storms can cause large amounts of this debris to fall into paddocks or pastures. Horses grazing in areas surrounded by trees and shrubs may inadvertently consume toxic leaves or seeds. Therefore, it’s crucial for horse owners to identify which vegetation poses a hazard and take precautions to protect their animals. In this article, we highlight poison trees and shrubs for horses that create risk, particularly during the autumn months.

What trees and shrubs are poisonous for horses?

Not all trees and shrubs are equally harmful to horses, and the level of toxicity can vary significantly. Thus, among the poison trees for horses, some pose greater risks than others. Generally, horses naturally won’t eat trees or shrubs, as many toxic plants have an unpleasant taste. However, during autumn, when grass growth slows down, horses may be more inclined to consume other plant material. Leaves or seeds lying in the grass may accidentally be ingested while grazing. Since dried leaves lose their sharp taste, horses are less likely to avoid them. The most common toxic trees for horses include beech, oak, maple, chestnut, buxus, and taxus.

Beech

Beech trees come in red and green varieties and can appear as trees or shrubs. In autumn, beech nuts fall from the trees and are poisonous to horses. While there are fewer nuts produced by beech hedges due to frequent trimming, they can still pose a risk. Eating a small number of beech nuts is generally harmless for your horse, but consuming several hundred grams can cause poisoning, with symptoms such as gastrointestinal issues and colic.

Oak

From oak trees, both oak leaves and green acorns are toxic for horses. They contain tannins, which are harmful to horses, though issues typically arise after consuming larger quantities. Nonetheless, the consequences can be severe and even fatal. So keep a close eye on horses near oak trees and consider fencing off areas with heavy acorn coverage.

Maple

In recent years there has been increasing research into a muscle disease for horses called Atypical Myopathy. So far it’s known that the seeds, leaves, and seedlings of the common maple contain toxins that may cause the disease. While of feather maple, only the seeds seem to be poisonous. Maple seeds, often called “helicopters,” fall in autumn, especially during windy conditions, and can spread over a wide area. Therefore, it is important to know which trees are in the vicinity of the pastures and regularly check pastures to remove fallen seeds and leaves.

Nonetheless, symptoms of Atypical Myopathy include fever, muscle tremors, stiffness, weakness, lying down, increased heart rate, and dark, coffee-coloured urine. If Atypical Myopathy is suspected, contact a veterinarian immediately and remove other horses from the affected pasture.

Chestnut

A recognizable tree in autumn, chestnut drops large quantities of nuts encased in spiky shells. Various parts of the tree, including bark, leaves, unripe nuts, and green shells, are poison for horses. The immature chestnuts can fall as early as late summer, and like green acorns, unripe chestnuts contain tannins. If a horse chestnut tree is in the pasture, consider fencing off the area around the tree or regularly removing fallen nuts to reduce the risk.

Buxus

Buxus, also known as boxwood, is often used for hedges or ornamental purposes, but many people aren’t aware of how toxic it is to horses. As an evergreen shrub, it remains green during autumn and winter. Although horses are unlikely to eat it, they may take a bite during the winter when little vegetation is available. Buxus is extremely toxic, and consuming just a few branches can be fatal. If a horse eats buxus, keep them calm and contact a veterinarian immediately.

Taxus

Many horse owners are aware of the dangers of taxus, also known as yew. Recognizable by its needle-like leaves and red berries, yew remains green throughout winter. The toxins in the taxus can cause heart failure in horses, with even a small twig being deadly. Therefore, avoid planting yew near stables or pastures.

Other poison trees for horses

In addition to the plants mentioned here, many other types of vegetation can be harmful to horses. Walk through your pasture and paddock to identify any shrubs and trees dangerous to horses that could pose a risk. Doing this at least once per season will help you spot potential threats, including plants that bloom at different times of the year. Plus, providing additional roughage or roughage mixes, such as Hartog Gras Mix or Hartog Compact Gras, to horses in pastures during colder months can decrease the risk of indigestion of toxic vegetation. Nonetheless, always consult a veterinarian if you suspect your horse has ingested toxic plant material.