Fall panicum (Panicum dichotomiflorum) toxicosis in three juvenile goats

Abstract

Consumption of certain grasses belonging to the genus Panicum has been found to cause hepatogenous photosensitization and crystal-associated cholangiohepatopathy in small ruminants, and liver disease in horses, in many areas of the world. We describe herein the clinical findings, microscopic lesions, and steroidal saponin analysis of Panicum dichotomiflorum associated with fatal toxicosis in 3 juvenile goats in Nebraska. The disease presentation in our case was fulminant, with anorexia, marked icterus, and death for all affected animals in less than a week. Photosensitization was not observed. The microscopic lesions consisted of severe crystal-associated cholangiohepatopathy and nephropathy, with aggregates of clear or refractile and birefringent, acicular crystals present within bile ducts, macrophages, hepatocytes, and renal tubules. High-performance liquid chromatography–mass spectrometry of the grass samples demonstrated that dichotomin was the major steroidal saponin present (0.89 µg/mg); protodioscin was also present (0.059 µg/mg). The findings were consistent with ingestion of steroidal saponins, and P. dichotomiflorum was identified as the predominant forage available.