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
Cattle, (horses).

Ingestion, over a prolonged period of time, of fresh plant material (uncommon) or of contaminated hay or silage.


The toxicity is not reduced or modified by drying. Ingestion of hay containing 5% horsetail for several days causes clinical signs.

Clinical features
Generally present as a subacute or chronic poisoning.

In cattle

In horses

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.

In cattle
No antidote. Symptomatic care only:

In horses