Tongue lesions in feedlot cattle associated with ergot alkaloid consumption.

Over 1200 heavy feedlot cattle presented with severe tongue lesions during a 7-month interval. Review of the literature and discussions with colleagues revealed previous similar outbreaks had occurred in Canada and the USA, with extensive investigations conducted and no cause identified. In the current outbreak, examination of the environment, feed, water, cattle behavior, and husbandry systems were conducted, as well as diagnostic testing including necropsy, histopathology, bacteriology, virology, and toxicology. All the initial testing to determine the cause of the lesions was unrewarding. As cases continued and increased during the second month, a further inspection of feedstuffs was undertaken. Hard clumps were identified in the dried distiller's grains with solubles feed additive (DDGS), and samples were submitted for additional mycotoxin analysis. Toxic concentrations of ergot alkaloids were detected, leading to a presumptive diagnosis of localised ergot toxicosis. Removal of the affected DDGS from the diet led to a decrease and eventual cessation of cases. This case report highlights the value of extensive collaborations among onsite and offsite colleagues when conducting detailed investigations on farm of a diagnostically challenging case. Key clinical message: This report describes a large outbreak of tongue lesions in feedlot cattle associated with ergot toxicosis. The report highlights the extensive investigation with collaboration among the producer, veterinarians, laboratory teams, and colleagues from further afield. Toxic concentrations of ergot alkaloids were present in hard clumps in the dried distiller's grains with solubles feed additive (DDGS), suggesting a possible etiology of localized ergot toxicosis.