Bracken produces a toxin that destroys the vitamin thiamine. Pigs are normally resistant to bracken poisoning and it needs in excess of six weeks of constant exposure particularly to fresh bracken shoots and the rhizomes.

Clinical signs

Sudden death is often the only sign, although prior to this respiratory distress may be seen associated with oedema or fluid in the lungs.

Diagnosis

This is based on history, clinical signs if seen and enzyme tests carried out on serum.

Treatment and control

• If sows are likely to have access to large amounts of bracken, injections of thiamine should be given every two weeks. Where clinical signs are seen all the group at risk should be injected with thiamine.