Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 2, 2008
Publication Date: July 1, 2009
Repository URL: http://www.pprl.ars.usda.gov
Citation: Green, B.T., Welch, K.D., Gardner, D.R., Stegelmeier, B.L., Davis, T.Z., Cook, D., Lee, S.T., Pfister, J.A., Panter, K.E. 2009. Serum Elimination Profiles of Methyllycaconitine and Deltaline in Cattle Following Oral Administration of Larkspur (Delphinium barbeyi). American Journal of Veterinary Research, 70(7):926-931. Interpretive Summary: We have shown using five Angus steers, that MLA and deltaline reach maximum serum concentrations by 10 hours after dosing and MLA has a slower E½ of 20.5 hrs when compared to deltaline’s 8.2 hrs. The longer MLA clearance suggests that a withdrawal time of 6 days be used to allow poisoned animals to clear these toxins. Our finding correlating serum MLA concentrations with increased heart rate further demonstrates that tachycardia is an early indicator of poisoning. More work is needed to better determine the biologic effect and mechanisms of MSAL and MDL interactions in combined intoxication and to determine why some animals or species are more susceptible to poisoning.
Technical Abstract: The objectives of this study were to describe the simple elimination kinetics of two abundant norditerpenoid alkaloids in larkspur, MLA and deltaline, and measure the heart rate response of intoxicated cattle over 96 hours. Five Angus steers halter broke, gentled, and habituated to metabolism crates were used. Tall larkspur (Delphinium barbeyi) was collected in the early flowering stage, dried, ground and administered orally to cattle in a single dose equivalent to 10.4 mg/kg MLA and 11.0 mg/kg deltaline. The cattle were housed in metabolism crates while heart rate was monitored continuously and serum samples obtained periodically throughout 96 hours of the experiment. No overt clinical signs of poisoning were seen during the entire 96 hours of the experiment. The heart rate reached a maximum of 79.0 ± 5.0 pbm at 17 hours post dosing. The Tmax values for MLA and deltaline were 8.8 ± 1.2 and 5.0 ±0.6 hours, respectively. The E½ values for MLA and deltaline were 20.5±4.1 and 8.2±0.6 hours, respectively. The results from this study have shown using five Angus steers, that MLA and deltaline reach maximum serum concentrations by 10 hours and that serum MLA concentrations are correlated with changes in heart rate. Based on the E½s calculated in this study, cattle that have consumed larkspur will have eliminated 99% of the serum MLA and deltaline by 144 hours.