Brake Fern (Pteridium aquiline)

Poisonous to Horses

Toxic parts and chemical: thiaminase in
leaves and stems when dry or fresh causes
a thiamine deficiency. Also called “brachen
staggers.”

Symptoms of Poisoning: Within 1 or 2
months of feeding on ferns symptoms of
thiamine deficiency appear. The horse
losses weight, becomes uncoordinated and
staggers. An arched back, wide stance and
severe muscle tremors with difficulty getting
up also appears. If not treated when these
symptoms appear the horse can die in 1 or
2 days
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