Special Veterinary Pathology

FACIAL ECZEMA

• Facial eczema caused by a mycotoxin, was first described in sheep in New Zealand
• Cattle are also affected
• It results from the mycotoxin, sporidesmin, produced by the fungus Pithomyces chartarum, which is a saprophyte on certain pastures
• It is usually associated with rye grass

Lesions

• The toxin is mainly a hepatotoxin
• The principal lesion from which the disease gets its name is the result of hepatotoxic photosensitization due to circulating phylloerythrin
• In sheep, face and ears are the most severely affected sites, whereas in cattle, the udder and teats are affected
• Microscopically, cholangio-hepatitis, characterized by necrosis of biliary epithelium, fibrosis and regenerative hyperplasia are the main hepatic lesions
• Focal hepatic necrosis and regenerative hyperplasia may be seen
• Haemorrhages in the wall of gallbladder and urinary bladder are common.