An owner was confronted with 30 dead sheep and at least that many staggering and apparently blind out of 1000 two-year old Merino ewes in May 2011 - The sheep had been moved onto a burnt lupin stubble in late April and then moved to a lush lucerne/phalaris/clover mixed pasture one week later. Three days later 30 sheep were dead with numerous others wandering into fences, trees and apparently unaware of their surroundings.
An investigation revealed that at least another 30-40 ewes were affected with a staggering gait, apparent blindness and a tendency to run into fences and head press. The remainder of the mob appeared normal when quietly driven.
The clinically affected sheep showed jaundice, lethargy, circling, head pressing and decreased awareness to stimuli. Euthanasia and examination of two of the affected animals showed severely jaundiced carcasses and bright yellow, waxy livers. Brain tissue was taken to rule out a TSE as well to determine the cause of the neuropathy.
Histopathology indicated a severe, diffuse, subacute, toxic hepatopathy consistent with Phomopsin intoxication and hepatic encephalopathy. TSE exclusion was negative.
In this case, the disease appeared unusually suddenly. This is presumably because the sheep were grazing a highly digestible protein pasture, which aggravated the hepatic damage and triggered the encephalopathy.