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Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/13/2018 Publication Date: 4/14/2018 Citation: Davis, T.Z., Stegelmeier, B.L., Lee, S.T., Green, B.T., Chitko-McKown, C.G. 2018. Effects of grinding and long-term storage on the toxicity of white snakeroot (Ageratina altissima) in goats. Research in Veterinary Science. 118:419-422. https://doi.org/10.1016/j.rvsc.2018.04.006. DOI: https://doi.org/10.1016/j.rvsc.2018.04.006 Interpretive Summary: White snakeroot is found in shaded areas throughout the Midwestern and Eastern United States. White snakeroot populations have varying toxicity and some only sporadically poison livestock. Poisoning is characterized by a myotoxic disease referred to as “trembles” that begins as muscular weakness and progresses over 7 to 10 days with continued exposure to myonecrosis, fibrosis and loss of function. The toxin in white snakeroot and the closely related but geographically and environmentally separated, rayless goldenrod was initially identified as tremetol. However, tremetol was later demonstrated to be a mixture of many different compounds. More recently, because of its toxicity in cell culture studies, microsomally activated tremetone was proposed as the toxin in white snakeroot and rayless goldenrod. Recent work has shown that goats develop white snakeroot and rayless goldenrod induced “trembles” when treated with 2% of their body weight daily for 10 days or two weeks. The results from this research demonstrate that white snakeroot that has been dried and stored for 5 years retains its toxic properties even though tremetone concentrations in the plant had decreased by approximately 80%. Additionally, grinding and storing white snakeroot at ambient temperatures for up to 4 months does not appear to affect either tremetone concentrations or the toxicity of the plant. Therefore if white snakeroot is harvested with other forages and contaminates stored or otherwise prepared feed, it should be assumed to be toxic and should not be fed to livestock. Technical Abstract: White snakeroot (Ageratina altissima) is toxic when ingested and can produce a disease called ‘milk sickness’ when livestock or humans drink tainted milk. The putative toxin in white snakeroot is commonly accepted as tremetone; however, its toxicity has not been demonstrated in vivo. It has been reported that the plant is less toxic after drying and grinding. The objectives of these studies were to determine: 1) the toxic effect of grinding white snakeroot 4 months prior to dosing and, 2) the toxic effect of storing white snakeroot at ambient temperature for 5 years. Dried white snakeroot, ground 1 day, 1 month, and 4 months prior to starting the study, was orally gavaged to goats at 2% of their body weight for up to 28 days or until they were minimally poisoned (minimal muscular weakness and increased serum creatine kinase (CK) activities. All four goats dosed with white snakeroot that had been ground 4 months previously and stored at room temperature were poisoned, became exercise intolerant, and increased serum CK activities to > 5,600 U L-1. White snakeroot stored for 5 years prior to grinding was also toxic as 3 of 5 goats developed clinical disease within only 6 days of dosing even though approximately 80% of the tremetone in the plant had disappeared during the 5-year storage period. The results from this study demonstrate that previous grinding and extended storage did not significantly alter white snakeroot toxicity. They also indicate that in some conditions, tremetone concentrations are not good indicators of toxicity and that other white snakeroot toxins or toxic tremetone degradation products remain in dried, stored white snakeroot. |
