Alsike Clover

Digger bee on Alsike clover. Photo credit: Bigstock/Dbengamin

Two disease syndromes in horses have been associated with grazing alsike clover: photo-sensitization and liver disease, which is less common.

• Affected species: Horses
• Low toxicity
• Common in some pastures
• Symptoms: Photo-sensitization (blistering of unpigmented skin when exposed to sunlight) and liver disease.
• Management: Remove horse from the pasture, manage pastures to promote grass, eliminate clover.
• Found in southern Canada, northern US states, and higher elevations in the western US

White and Red Clover

White and red clover. Photo credit: BigStock/Greywall Studio

Horses grazing pastures with red and white clover may become affected by “slobbers.” The toxin behind the slobbers, slaframine, is produced by a fungus that afflicts clovers, which stimulates the salivary glands and causes horses to drool.

• The clover plant itself is not toxic.
• Slaframine is produced by “black patch fungus,” Rhizoctonia, which grows on clover during periods of stress.
• Symptoms: Salivation and drooling
• Affected species: Only horses
• Management: Remove horses from clover and provide plenty of fresh water
• Found throughout the continental United States, Europe & Asia

Tall Fescue

Tall fescue meadow grass. Photo credit: BigStock/V_Nikitenko

Endophyte-Infected Tall Fescue – Kentucky 31

• Common grass in this region
• Large leaf blades with sharp edges and prominent veins, shiny on lower surface
• Not a preferred plant until after frost
• Kentucky 31 tall fescue contains an endophyte that produces a toxin called ergovaline
• The toxin is found in all plant tissues and seeds.
• Affected species: sheep, cattle, goats, horses
• Mares may have long pregnancies, abort foals, or have other reproductive problems if they graze infected fescue in the last three months of pregnancy.
• Endophyte-free tall fescue varieties are available commercially. Novel-endophyte or “endophyte-friendly” varieties do contain an endophyte for enhanced growth but do not produce ergovaline and are safe for pregnant mares to graze.
• Found from the Pacific Northwest to the southern states in low-lying pastures. Also Europe & North Africa.

Buttercup Species

Tall Buttercup. Photo Credit: Montana Statewide Noxious Weed Awareness and Education Program, Montana State University, Bugwood.org

• All livestock are affected.
• Toxicity – low
• Common in pastures and marshes
• Poisonous part – leaves and flowers
• Symptoms – irritated tissues in the mouth and throat. Affects the gastrointestinal system (colic, diarrhea), causes excessive salivation.
• Buttercups are distributed throughout the world and are especially common in woods and fields of the north temperate zone.

Pokeweed

Common Pokeweed. Photo Credit: Joseph M. DiTomaso, University of California – Davis, Bugwood.org

• Affects all livestock – especially pigs.
• Toxicity – moderate
• Found in rich, disturbed soils such as barnyards, moist woodlands and pastures
• Poisonous part – all parts, but mainly the roots
• Symptoms – Affects the gastrointestinal system (colic and diarrhea) and central nervous system (convulsions).
• Cooked berries are sometimes used in pies
• It is found from Washington south to California then east through Arizona and New Mexico to the Atlantic coast, north to Nebraska, Minnesota and Maine.

Nightshade Species

Bittersweet Nightshade. Photo Credit: Joel Floyd, USDA APHIS PPQ, Bugwood.org

• All livestock are affected.
• Toxicity – moderate
• Found in disturbed soils, rich pastures, and woods
• Poisonous part – berries and vegetation
• Symptoms – Affects central nervous system (trembling, paralysis, shock, coma); gastrointestinal system (colic, diarrhea and impaction)
• A native to Europe, North Africa, and Western Asia. It is now naturalized in a limited region of the Northeast and more widely throughout the Pacific Northwest.

Horsenettle

Horsenettle. Photo Credit: Ohio State Weed Lab, The Ohio State University, Bugwood.org

• All livestock are affected.
• Toxicity – moderate
• Distribution – pastures, cultivated fields, hay fields
• Poisonous part – all parts, especially berries. Remains toxic in hay.
• Symptoms – Affects the gastrointestinal (salivation, colic, diarrhea) and central nervous system (muscle tremors, weakness, depression)
• The plant is invasive throughout much of temperate North America, as well as parts of Europe, Asia, and Australia.

Poison Hemlock

Poison Hemlock. Photo Credit: Jan Samanek, Phytosanitary Administration, Bugwood.org

• All livestock are affected.
• Toxicity – extremely toxic, 4-5 pounds will kill a 1,000 pound animal
• Distribution – disturbed or waste areas, roadsides, ditches
• Poisonous part – all parts are extremely toxic
• Symptoms – Affects the central nervous system (blocked spinal cord reflexes, muscle tremors, in-coordination, paralysis), frequent urination, sudden death due to respiratory failure.
• Native to Europe, western Asia, and North America
  

  Water Hemlock

•  Photo Credit: Elmer Verhasselt, Bugwood.org
• • 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, and wet pastures
  • Symptoms – Affects central nervous system, causing nervousness, breathing difficulties, muscle tremors, collapse, convulsions, death
  • These hemlock species are found throughout North America and Europe
    

    Jimson Weed

    

  •  

    Jimson Weed. Photo Credit: Howard F. Schwartz, Colorado State University, Bugwood.org

    • 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
    • It 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
    • This plant is probably native to Eastern North America, but is now found, along with other species of the genus Datura, in many countries around the world

    White Snake Root

    

    White Snakeroot. Photo Credit: John Triana, Regional Water Authority, Bugwood.org

    • 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
    • The Native Range for White Snake Root is from Texas to North Dakota, and East to the Atlantic Ocean, covering all states and provinces between

    Milkweed

    

    Common Milkweed. Photo Credit: Richard Gardner, Bugwood.org

    • 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
    • Found in most of the eastern United States and the eastern most prairie states as well as southern Canada from New Brunswick to Saskatchewan

    Cherry (Black, Pin, Choke)

    

    Black Cherry. Photo Credit: Richard Webb, Bugwood.org

    • 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
    • Ranges from southeastern Canada through the eastern United States west to eastern Texas, with disjunctive populations in central Texas and mountains of the southwestern United States, Mexico, and Guatemala

    Red Maple

    

    Red Maple. Photo Credit: Paul Wray, Iowa State University, Bugwood.org

    • 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
    • They’re found from Maine west to Minnesota, south to Texas, and east to Florida

    Box Elder Maple

    

    Box Elder. Photo Credit: https://www.flickr.com/photos/cricketsblog/26262670762 Melissa McMasters

    Seeds from the boxelder maple cause the equine muscle disease Seasonal Pasture Myopathy.

    • Affected species – horses
    • Toxicity – high. Quantity required for toxicity is unknown, but SPM is 75-90% fatal
    • Poisonous parts – Seeds contain toxin, hypoglycen A, which interferes with fat metabolism and breaks down respiratory and muscle cells
    • Only female boxelder trees produce seeds. Male trees are not dangerous
    • Symptoms – Tremors, weakness, stiffness, dark urine, rapid breathing, and death – usually within 48 hours
    • It is found from New York to central Florida; west to southern Texas; and northwest through the Plains region to eastern Alberta, central Saskatchewan and Manitoba; and east in southern Ontario

    Black Walnut

    

  • Black Walnut. Photo Credit: Jason Sharman, Vitalitree, Bugwood.org

    • Species affected – horses
    • Toxicity – moderately toxic
    • Poisonous parts – bark, root, nuts contain juglone, which may be involved in toxicity
    • Walnuts and hulls on the ground may become moldy and cause toxicity if consumed
    • Symptoms – Horses bedded on shavings or sawdust containing black walnut develop colic, edema and laminitis
    • No amount of black walnut is acceptable in bedding
    • If removing trees or branches in pastures, be careful to clean up all sawdust left in the pasture.
    • It grows throughout the central and eastern parts of the United States
    • Found on a variety of sites, grows best on good sites in coves and well-drained bottoms in the Appalachians and the Midwest.

    Oaks (Black, Chestnut, Red, Pin, White)

    

    Red Oak Leaves. Photo Credit: https://www.publicdomainpictures.net

    • Affects cattle, sheep, horses and pigs.
    • Toxicity – moderately toxic
    • Poisonous part – New young leaves most toxic, acorns more toxic when green than when mature
    • Symptoms – Poor appetite, weight loss, diarrhea, increased drinking, increased urination, kidney failure, edema, death
    • Oak trees can be found growing in India, America, England, China, and Japan

    Buckeye or Horse Chestnut

    

    Horse Chestnut. Photo Credit: John Ruter, University of Georgia, Bugwood.org

    • Affects all livestock
    • Toxicity – moderate to high
    • Poisonous part – leaves, seeds, young sprouts; poisoning in spring due to early sprouting
    • Symptoms – Affects gastrointestinal and central nervous systems
    • Grows from the southern United States to the prairies of western Canada

    Black Locust

    

    Black Locust. Photo Credit: Jan Samanek, Phytosanitary Administration, Bugwood.org

    • Affects all livestock species
    • Toxicity – moderate to high
    • Poisonous parts – leaves, seeds, bark, wood (fence posts)
    • Symptoms – Causes severe gastritis, colic, depressionnative
    • Grows from Pennsylvania through the Appalachians to northern Georgia and westward to Arkansas and Oklahoma. Can also be found in California

    Rhododendron, Mountain Laurel, Azalea

    Rhododendron. Photo Credit: Richard Webb, Bugwood.org

    
    

  • • Affects all livestock.
    • Toxicity – high
    • Poisonous part – all parts
    • Symptoms – Stomach irritation, abdominal pain, abnormal heart rate and rhythm, convulsions, coma, death
    • Generally grows along the Atlantic coast from Nova Scotia to the upper Carolina’s, along both sides of the Appalachian Mountains and in southern Ontario, Michigan, Illinois, Wisconsin, Ohio, Pennsylvania, New York

    Bracken Fern

    

    Bracken Fern. Photo Credit: David Stephens, Bugwood.org

    • All livestock are affected.
    • Toxicity – low to moderate
    • Distribution – moist forests
    • Poisonous part – All plant parts contain toxin which destroys vitamin B1
    • Symptoms – Weight loss, weakness, gait abnormalities, abnormal heart rate and/or rhythm, inability to rise, death
    • Some animals develop a preference for this plant
    • It is widespread throughout the northeast United States and the southern part of Canada

Yew (English or Japanese)

Yew. Photo Credit: Richard Webb, Bugwood.org

• Affects all livestock and humans
• Toxicity – Extreme
• Poisonous part – all plant parts, especially high in leaves during winter
• Symptoms – Muscle trembling, lack of coordinaion, colic, slow heart rate, death
• Yews are commonly planted as landscape shrubs on home properties and even show grounds
• Primarily ranging in North America from Manitoba, Minnesota and Iowa eastward to the coast and south as far as Tennessee and North Carolina

Stay Safe Out There!