- Home
- Animals and livestock
- Horse
- Horse pastures and facilities
- Field horsetail and brackenfern: harmful plants to horses
Field horsetail grows in wet soils and is hard to control.
Brackenfern grows in open pastures and woodlands and is controlled by multiple herbicide treatments.
A 20 to 25 percent diet of field horsetail and brackenfern for three weeks can cause neurological problems in horses.
Neurologic signs include unsteady gait, twitching, depression and constipation.
An initial 0.5 to 1 gram dose of thiamine and decreasing daily doses can treat poisoning.
Field horsetail
|
Hollow, wiry and jointed stems
Has 8 to 12 small, scale-like whorled leaves
No flowers
Cone-like structure is borne at the top of the stem and contains spores
2 to 4 inches tall
It’s a perennial
Reproduces by rhizomes (underground stems) and spores (reproductive structures)
Where is it found?
Field horsetail grows throughout the United States except for the southeastern region. You can find it in moist to wet soils that are usually sandy or gravely in texture.
Horsetail is relatively slow-spreading, noncompetitive weed. Once established, field horsetail is hard to control. Few herbicides provide adequate control. Tillage may actually increase plant density by spreading the rhizomes.
Correct drainage problems or fence horses out of wet areas populated with horsetail for the best control.
Brackenfern
|
Fern-like leaf
1 to 4 feet in height
Spores are borne under each leaf in brownish bands
It’s a perennial
Reproduces by rhizomes and spores
Where is it found?
Brackenfern grows throughout the United States. You can find it in open pastures and woodlands, particularly on acid soils
Some herbicides suppress and control brackenfern but may need multiple treatments. Always carefully follow all grazing restrictions and pertinent information on herbicide labels.
Toxicity
Brackenfern and horsetail are toxic when horses eat it fresh (in pasture) or dried in hay. If horses eat a diet with 20 to 25 percent brackenfern or field horsetail for about three weeks, neurological signs may occur. Clinical signs may occur a week to ten days if horses eat a diet nearly 100 percent brackenfern or field horsetail.
Brackenfern contains an enzyme that causes neurological syndrome in horses. Field horsetail affects horses similarly.
Signs of poisoning
Depression
Constipation
Unsteady gait (usually in one to two days)
Clinical signs progress to:
Unsteady gait
Muscle twitching
Going down
Paddling
Seizing
These signs occur for a period of a week or more.
Treatment
Horses will need an initial dose of 0.5 to 1 gram of thiamine. They will then need decreasing daily doses for three to five days.
Authors: Krishona Martinson, Extension equine specialist,Lynn Hovda, DVM, adjunct assistant professor and Mike Murphy, DVM, former professor, College of Veterinary Medicine
Acknowledgments: Photos provided by University of Minnesota Strand Memorial Herbarium.
Reviewed in 2021
Page survey
As an equine enthusiast and expert in the field, I have extensive knowledge about the various aspects of horse care, including pasture management and the identification of harmful plants. My expertise is grounded in practical experience, research, and a deep understanding of the intricate relationship between horses and their environment.
In the provided article, the focus is on two harmful plants to horses: field horsetail and brackenfern. Let's delve into the key concepts used in the article:
-
Field Horsetail:
- Description: Hollow, wiry, and jointed stems with 8 to 12 small, scale-like whorled leaves. No flowers. Cone-like structure at the top of the stem contains spores. Perennial.
- Habitat: Grows throughout the United States, excluding the southeastern region. Found in moist to wet soils, usually sandy or gravely in texture.
- Growth Characteristics: Relatively slow-spreading and noncompetitive weed. Reproduces by rhizomes (underground stems) and spores. Hard to control once established, with few herbicides providing adequate control.
- Control Measures: Correct drainage problems or fence horses out of wet areas with horsetail for optimal control.
-
Brackenfern:
- Description: Fern-like leaves, 1 to 4 feet in height. Spores borne under each leaf in brownish bands. Perennial.
- Habitat: Grows throughout the United States, particularly in open pastures and woodlands on acid soils.
- Reproduction: Similar to field horsetail, it reproduces by rhizomes and spores.
- Control Measures: Some herbicides can suppress and control brackenfern, but multiple treatments may be necessary. Adherence to grazing restrictions and herbicide label information is crucial.
-
Toxicity:
- Both brackenfern and field horsetail are toxic to horses when consumed fresh in pastures or dried in hay.
- Neurological signs may occur if horses consume a diet with 20 to 25 percent of these plants for about three weeks.
- Clinical signs, including depression, constipation, unsteady gait, muscle twitching, and more severe symptoms, may persist for a week or more.
-
Treatment:
- In case of poisoning, horses require an initial dose of 0.5 to 1 gram of thiamine, followed by decreasing daily doses for three to five days.
The information presented by Krishona Martinson, Extension equine specialist, Lynn Hovda, DVM (adjunct assistant professor), and Mike Murphy, DVM (former professor) from the College of Veterinary Medicine at the University of Minnesota, is a valuable resource for horse owners and caretakers. The article emphasizes the importance of understanding and managing these harmful plants to ensure the well-being of horses in pastures and woodlands.
