Equisetum arvense (field
horsetail, common horsetail, bottle brush, Dutch rushes, paddock-pipes, pewterwort,
shave brush), Equisetum palustre (marsh horsetail). A member of the plant
family EQUISETACEAE. Perennial herbaceous plants, with short upright, green stems
arising from creeping rhizomes. The fertile stems are usually irregularly branched;
the sterile stems do not have branches but have a spore-bearing sword-like tip.
Animals most affected
Ingestion, over a prolonged period of time, of fresh plant material (uncommon) or
of contaminated hay or silage.
- A thiaminase with anti-vitamin B1 activity, responsible for weakness and falls in
- Alkaloids: equisetine, heterosides, galuteoside;
- A high silica content.
The toxicity is not reduced or modified by drying. Ingestion of hay containing
5% horsetail for several days causes clinical signs.
Generally present as a subacute or chronic poisoning.
Weakness, fall in milk production;
Difficulty in walking and in getting up
(excitation and blindness have been reported in a few cases)
Hyperexcitability, progressive weakness, loss of weight.
Note: ingestion of a large amount of the plant material causes rapid onset of
salivation, severe colic and excitation. Possibly death.
Hepatic and renal degeneration.
No antidote. Symptomatic care only:
Adsorbents, gastric demulcents