If an animal has eaten this plant, the ASPCA Animal Poison Control Center is (888) 426-4435, as printed on the record this page reproduces. A consultation fee may apply.
This page quotes a published document. Everything below in quotation marks is copied word for word from ASPCA Animal Poison Control Center: Scouring Rush, published by ASPCA APCC and retrieved on 2026-09-16. The quotations are excerpts; the document itself is linked and is the authority. Nothing has been reworded.
According to the ASPCA Animal Poison Control Center record, Scouring Rush (Equisetum arvense, family Equisetaceae) is toxic to horses. Toxic principles: Thiaminase. Clinical signs listed: The plant is commonly ingested when horses have very little suitable vegetation to graze on; ingestions over several days or weeks may result in adverse clinical effects. The toxic component breaks down thiamine (an essential nutrient for central nervous system function and metabolism). Clinical signs include weight loss, central nervous system disorders, muscle weakness gradually progressing in severity, convulsions and death. The record was retrieved on 2026-09-16 and is linked below.
The record
- Scientific name
- Equisetum arvense
- Family
- Equisetaceae
- Additional common names
- Field Horsetail, Common Horsetail, Western Horsetail
- Toxicity
- Toxic to Horses
- Toxic principles
- Thiaminase
- Clinical signs
- The plant is commonly ingested when horses have very little suitable vegetation to graze on; ingestions over several days or weeks may result in adverse clinical effects. The toxic component breaks down thiamine (an essential nutrient for central nervous system function and metabolism). Clinical signs include weight loss, central nervous system disorders, muscle weakness gradually progressing in severity, convulsions and death.
Where this comes from
This is the ASPCA Animal Poison Control Center record for Scouring Rush, at https://www.aspca.org/pet-care/aspca-poison-control/toxic-and-non-toxic-plants/scouring-rush, retrieved on 2026-09-16. The fields above are the record’s own, shown without change. The ASPCA keeps the record current; the page here is a copy from that date.
This page is information, not a prescription. The right dose for an animal depends on its weight, its age, what else it is taking and what is wrong with it. Those are judgements only the veterinarian who has examined your animal can make. Ring your practice before giving anything.
Sources
- ASPCA Animal Poison Control Center: Scouring RushASPCA APCC · retrieved 2026-09-16
“The plant is commonly ingested when horses have very little suitable vegetation to graze on; ingestions over several days or weeks may result in adverse clinical effects. The toxic component breaks down thiamine (an essential nutrient for central nervous system function and metabolism). Clinical signs include weight loss, central nervous system disorders, muscle weakness gradually progressing in severity, convulsions and death.” (Clinical Signs)
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