Hawkins et al.. demonstrated the toxic effects of CYN by mouse bioassay, using an extract of the original Palm Island strain. Acutely poisoned mice displayed anorexia, diarrhoea and gasping respiration. Autopsy results revealed haemorrhages in the lungs, livers, kidneys, small intestines and adrenal glands. Histopathology revealed dose-related necrosis of hepatocytes, lipid accumulation, and fibrin thrombi formation in blood vessels of the liver and lungs, along with varying epithelial cell necrosis in areas of the kidneys.
A more recent mouse bioassay of the effects of cylindrospermopsin revealed an increase in liver weight, with both lethal and non-lethal doses; in addition the livers appeared dark-coloured. Extensive necrosis of hepatocytes was visible in mice administered a lethal dose, and some localised damage was also observed in mice administered a non-lethal dose.