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United States Department of Agriculture

Agricultural Research Service

Title: Toxicity of a Pyrrolizidine Alkaloid, Riddelliine, in Neonatal Pigs

Authors
item Stegelmeier, Bryan
item James, Lynn
item Panter, Kip
item Molyneux, Russell
item Gardner, Dale
item Schoch, Thomas
item Lee, Stephen
item Ralphs, Michael
item Pfister, James

Submitted to: Poisonous Plants Symposium Proceedings
Publication Type: Book / Chapter
Publication Acceptance Date: May 20, 2003
Publication Date: November 1, 2003
Citation: Stegelmeier, B.L., James, L.F., Panter, K.E., Molyneux, R.J., Gardner, D.R., Schoch, T.K., Lee, S.T., Ralphs, M.H., Pfister, J.A. 2003. Toxicity of a pyrrolizidine alkaloid, riddelliine, in neonatal pigs. Poisonous Plants Symposium Proceedings.

Interpretive Summary: Pyrrolizidine alkaloids (PAs) are plant poisons that damage livestock, wildlife and occasionally humans. Young animals are especially sensitive to PA poisoning. The purpose of this work is to determine the effects of animal age on PA toxicity in pigs. Five groups of 12 pigs at 0, 3, 6, 12, and 52 weeks of age were dosed with a pyrrolizidine alkaloid called riddelliine. All dosed animals developed severe liver disease with icterus, weight loss and microscopic changes of liver cell swelling, degeneration and necrosis with hemorrhage and collapse of tissue structure. Blood markers of poisoning (serum aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase, bilirubin, and bile acids) were also increased. The clinical, histological, and blood changes were compared between the different doses and ages. Pigs at 3 and 6 weeks of age had significantly higher responses to similar doses of riddelliine when ncompared to similar doses given to other ages. There were no age-related differences in older pigs as 12 weeks old pigs had changes similar to those of yearling animals. The results suggest that weanling pigs near 3-6 weeks of age are most susceptible to PA poisoning and that age susceptibility is an important consideration in determining exposure risk.

Technical Abstract: Pyrrolizidine alkaloids (PAs) are common plant toxins that poison livestock, wildlife and occasionally humans. Neonatal animals may be especially sensitive to PA toxicity. The purpose of this work is to document the effects of animal age on PA toxicity in pigs. Five groups of 12 pigs at 0, 3, 6, 12, and 52 weeks of age were dosed with purified riddelliine at doses of 0, 5, 10 and 20 mg kg-1 for 14 days. After dosing the pigs were euthanized, necropsied and tissues were collected for histologic and chemical studies. Blood was collected throughout the study and at necropsy for hematology, serum biochemical and chemical studies. All animals dosed at 20 mg kg-1 developed severe hepatic disease characterized by clinical icterus, weight loss and histologic lesions of hepatocellular swelling, degeneration and necrosis with hemorrhage and sinusoid collapse. Serum aspartate aminotransferase, alkaline phosphatase, ,gamma glutamyl transferase, bilirubin, and bile acids were also increased. The clinical, histological, and serum biochemical changes were compared between the different doses and ages. Pigs at 3 and 6 weeks of age had significantly higher responses to similar doses of riddelliine when compared to similar doses given to other ages. There were no age-related differences in older pigs as 12 weeks old pigs had changes similar to those of yearling animals. The results suggest that weanling pigs near 3-6 weeks of age are most susceptible to PA poisoning and that age susceptibility is an important consideration in determining exposure risk.

Last Modified: 10/19/2014
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