Outbreaks of photosensitisation and deaths in cattle due to Myoporum aff. Insulare R. Br. toxicity.

Outbreaks of photosensitisation and deaths in cattle on 5 farms in Victoria occurred following access to Myoporum affinity insulare. Signs were observed 2 to 6 days after access to myoporum trees or pruned branches and included depression, anorexia, photosensitisation, constipation, agalactia, jaundice, and mucosal petechiation. Serum gamma glutamyl transferase and aspartate amino transferase levels were elevated in all cases. Gross findings in fatally intoxicated cows consisted of widespread haemorrhages and pale yellow mottling of the liver. Distinctive histological lesions of periportal hepatic necrosis and bile duct proliferation were seen in all cases. An 8-month-old heifer given 30 g/kg fresh minced leaves by stomach tube died approximately 70 h after initial dosing. Post-mortem findings of widespread haemorrhage and hepatic periportal necrosis and bile duct proliferation were identical to those of field cases.