Mortality of a white rhinoceros (Ceratotherium simum) suspected to be associated with the blue-green alga Microcystis aeruginosa

Three of four white rhinoceroses died within 3 months of introduction into a game reserve. Post-mortem examination of one of the animals revealed marked hepatomegaly with haemorrhage and severe necrosis of the liver as well as numerous ecchymoses and petechiae in the subcutaneous tissue and subserosa of the thorax, abdomen and diaphragm. Histologically, severe hepatic necrosis was the most significant finding. Algae recovered from the dam from which the animals drank were identified as Microcystis aeruginosa. A diagnosis of suspected Microcystis poisoning was made.