The Toxicity of Ash Trees to Horses

Horses are herbivores that will consume or at least sample almost all forms of greenery available to them. If a horse consumes a toxic plant, symptoms can range from relatively mild diarrhea to trouble breathing, organ failure and death. Ash trees are commonly found in horse pastures because they are considered to be safe for horses.

Ash trees are a popular choice for horse pastures and facilities because they are not toxic to horses. Horses can consume ash tree leaves and bark without risk of becoming sick, though most horses will probably not want to eat ash trees unless there is very little roughage for them to graze on.

You can determine if the trees in your pasture are ash trees by examining them closely. Ash trees are a member of the Fraxinus genus. They have branches that grow opposite to one another on each side of the tree's main branches. They also have compound leaf growth pattern.

Mountain ash is not a true ash tree. It is part of the Sorbus genus and is not related to other ash trees. According to the Pierce Conservation District in Pierce County, Washington, mountain ash may be poisonous to horses and other livestock. Possible symptoms of mountain ash ingestion include breathing problems, behavior abnormalities, diarrhea and may even be fatal if ingested in very large quantities.

The ASPCA publishes a list of toxic and horse-safe plants that you should check any new plants against before you plant them within reach of your horses. Most horses do not consume toxic plants intentionally because they often have an unpleasant taste or texture. You can minimize the risk of your horse consuming a toxic plant by providing plenty of quality hay and grass to your horses at all times.