Facial eczema caused by sporidesmin toxin from pasture fungi causes severe liver damage and photosensitisation in sheep, with significant welfare consequences in warm wet summers.
Sheep with facial eczema develop crusting, weeping and sloughing of sun-exposed skin on the face, ears and udder — highly painful and visible welfare harm. The underlying liver damage causes chronic metabolic dysfunction even when skin lesions heal. Severely affected animals require euthanasia as liver damage is irreversible. Preventive zinc dosing, spore count monitoring and moving stock off affected pasture reduces the welfare burden substantially in high-risk summers.