The pathology of experimental Lasiospermum bipinnatum (Thunb.) Druce (Asteraceae) poisoning in sheep. II. Pulmonary and miscellaneous lesions.

Poisoning with the plant Lasiospermum bipinnatum was studied in 9 lambs at various dose levels. Dyspnoea and tachypnoea, which were dose-related, were observed in 4 of the lambs. Gross and microscopic pulmonary lesions were found in all the lambs receiving plant material originating from one source but not in those given plant from another locality. The severity of the lesions appeared to be dose-dependent. Macroscopic lesions included pulmonary and mediastinal emphysema, congestion and oedema. Microscopically Clara cell hypertrophy and hyperplasia, and interstitial pneumonia were the most outstanding findings. It is speculated that the pulmonary lesions were induced by a furanosesquiterpene or tryptophan or a combination of both of these toxins in the dosed plant material. Miscellaneous and inconsistent lesions observed in the experimental animals included widespread haemorrhage (1 lamb), transudations into the body cavities and adrenocortical hyperplasia.