Plants Toxic to Horses

Water Hemlock

• All livestock are affected.
• Toxicity - extremely toxic (a piece of root the size of a walnut will kill a cow in 15 minutes)
• Poisonous part - all parts, especially the root
• Distribution - marshes, ditches, wet pastures
• Symptoms - Affects central nervous system, causing nervousness, breathing difficulties, muscle tremors, collapse, convulsions, death.

Jimson Weed

• All animals affected, including chickens.
• Toxicity – extreme
• Distribution - crop fields, waste areas, barnyards
• Poisonous part - entire plant, especially seeds
• Symptoms - Affects central nervous system. Has hallucinogenic properties
• Jimson weed has a strong, foul odor and an unpleasant taste. Animals are often poisoned when feed is contaminated with jimson weed seed.
• Jimson weed is an annual plant; mowing helps eliminate these plants.

White Snake Root

• Affects horses, cows, sheep, goats, pigs and chickens.
• Toxicity - high
• Distribution - common in moist areas, edge of woods, along roads
• Poisonous parts - leaves and stems
• Symptoms - trembling, stiffness, ataxia, coma, death
• White snake root's toxin, trematol, passes to humans in milk resulting in milk sickness.

Milkweed

• Affects livestock and poultry.
• Toxicity - high
• Distribution - swamps, bogs, dry fields and pastures
• Poisonous part - entire plant
• Symptoms - weakness, seizures, respiratory difficulties, coma, death.
• Milkweed's latex-like sap makes the plant very unpalatable.

Cherry (Black, Pin, Choke)

• Affects all livestock, most dangerous to ruminants.
• Toxicity - highly toxic
• Poisonous part - leaves, twigs, bark and seeds contain cyanide, wilted leaves are more toxic than the rest.
• Symptoms - anxiety, breathing problems (suffocation), staggering, convulsions, collapse, death.

Red Maple

• Only horses and ponies are reported to be affected.
• Toxicity - extremely toxic (1.5-3 pounds cause toxicity)
• Poisonous part - wilted or dried leaves
• Symptoms - breathing difficulties, jaundice, dark brown urine, death.
• Toxins (gallic acid and others) destroy red blood cells. Red maple hybrids, such as silver and sugar maple, also have toxins.
• Leaves are most dangerous when wilting (i.e. a branch comes down during a storm), but fallen autumn leaves are also toxic for 30 days or so and should be removed from pastures.