Lupinosis refers to the liver disease caused by ingestion of a fungal toxin (phomopsin) on stubble of lupin crops. The toxin is produced in increasing amounts on the stem after the plant dies over summer, especially after rain, dew or high humidity.
Animals most at risk are hungry sheep, heavily stocked on lupin stubbles, with little else to eat. All lupin stubbles are dangerous. Animals intended for live export could have recently grazed high risk stubbles and may develop clinical signs in the assembly point over ensuing weeks. The stresses of transport and handling in assembly points may exacerbate expression of disease and large numbers may die.
Signs include depression, anorexia, jaundice, collapse and death in a large proportion of mobs. Survivors may have chronic illthrift and are susceptible to photosensitisation and chronic copper poisoning.
Necropsy findings in acute cases include jaundice, swollen yellow to orange livers, ascites and oedema of the mesenteries and gut wall. In chronic cases there are misshapen, hard, small livers.
Laboratory confirmation requires sections of liver and kidney in buffered formalin for histology.
Differential diagnoses include pyrrolizidine alkaloid poisoning from plants such as heliotrope and Paterson's Curse, or copper poisoning.
There is no effective treatment. Nurse mildly affected animals. Provide shade and hay. Ensure animals do not have access to other compounds that may be a problem if liver function is compromised such as copper. Severly affected animals should be humanely euthanased.
Avoid sourcing sheep that have grazed lupin stubbles, especially after rain, dew or humid weather.