Shrubs That Are Poisonous to Horses

Horses may gain access to poisonous plants on trail rides.

Nearly all pastures contain toxic plants or shrubs, but those plants often have an unpleasant taste that makes them unpalatable to horses, according to the Rutgers Equine Science Center. However, even well-fed horses may sample plant material because other horses or animals are eating from or near it, and horses may try plants out of curiosity or boredom. In some cases, that is all it takes to make your animals seriously ill or even lead to death. In addition to precautions at home, take care when traveling with your horses to new, unfamiliar areas.

Black Locust

The Black Locust is toxic in its leaves, stems and seeds. Keep it far away from your horse.

Black locust can grow in tree or shrub form and is common to fence lines. Its bark, twigs, sprouts, leaves and seeds are all poisonous. The plants' poisons include the glycoside robitin and the phytotoxins robin and phasin, according to the Ohio State University Extension, which warns that owners should keep black locust seed pods from falling into water tanks. Avoid using black locust sawdust as a bedding material, and avoid planting the shrubs around pastures and barns. If you must plant black locust, locate the shrubs far out of reach of your horses. Symptoms of poisoning by black locust include horses standing with their feet spread, posterior paralysis and irregular heartbeat. Black locust has the potential to cause death from cardiac failure.

Yew

Yew branches can swiftly bring on death if ingested by your horse.

All types of yew shrubs are poisonous. Taxine alkaloids are the poisons present in the all parts of the plants but the arils of the seeds. These toxins affect the cardiac and nervous systems of animals. Ingestion of a very small amount of plant material can cause death in horses. Symptoms of yew poisoning include difficulty breathing, vomiting and diarrhea, convulsions, coma and death. Death can be swift and without warning.

Mountain Laurel

All parts of mountain laurel shrubs contain the toxic resinoid andromedotoxin, and the leaves, and twigs also contain the cardiac glycoside arbutin, warns the Ohio State University Extension. Ingestion of mountain laurel causes symptoms ranging from bloating and trouble breathing to watering from the eyes, nose and mouth. Convulsions and death can result in horses.

Privet

Ingestion of the leaves or fruit of privet hedges can cause symptoms ranging from diarrhea to death in horses, according to the Ohio State University Extension, which notes that these plant parts contain toxic glycosides including ligustrin and syringin which irritate the gastrointestinal system. The Rutgers Cooperative Extension recommends that you avoid allowing horses around yew, privet and mountain laurel at all costs because of the severe toxicity of the plants and the potential for the plants to be lethal.

References

• Ohio State University Extension: Horse Nutrition: Trees and Shrubs
• Rutgers Cooperative Extension; Odd Things That Horses Eat; Sarah L. Ralston, VMD, Ph.D. dACVN
• Rutgers Equine Science Center; Ask the Expert -- Poisonous Plants; Carey Williams, Ph.D., et al.; 2009
• Cornell University Department of Animal Science: Scientific Name: Robinia Pseudoacacia
• DVM360; Toxicology Brief: The Dangers of Yew Ingestion; R.B. Cope, BSc, BVSc, Ph.D.; September 2005
• Utah State University Extension; Yew Had Better Watch Out!; Clell V. Bagley, DVM, et al.; July 1997

Resources

• Cornell University Department of Animal Science: Plants Poisonous to Livestock
• Cooperative Extension System; What Plants Are Toxic to Horses; March 2009
• TheHorse.com; Safe Paths, Safe Plants; Sushil Dulai Wenholz
• Texas AgriLife Extension: Toxic Plants of Texas: Black Locust