Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 2011
Publication Date: August 1, 2012
Repository URL: http://avmajournals.avma.org/doi/pdf/10.2460/ajvr.73.8.1318
Citation: Green, B.T., Welch, K.D., Gardner, D.R., Stegelmeier, B.L., Pfister, J.A., Cook, D., Panter, K.E. 2012. Toxicokinetics of norditerpenoid alkaloids from low larkspur (Delphinium andersonii) orally administered in cattle. American Journal of Veterinary Research. 73(8): 1318-24. Interpretive Summary: Cattle are poisoned by toxic alkaloids in Delphinium species (larkspur). Delphinium andersonii (Anderson's larkspur) is an important toxic plant in Idaho causing significant death losses to cattle where it grows. We determined the clearance times of toxic alkaloids from Anderson's larkspur so that an accurate assessment of risk to cattle can be made. This study documented differences in toxicokinetics of Anderson's larkspur compared to other previously examined larkspur. These results support the recommendation that approximately seven days are required to clear 99% of the toxic alkaloids from the serum of animals administered either species of larkspur.
Technical Abstract: Objective- To better assess low larkspur toxicity and manage treatment of poisoned animals, more knowledge is needed about the serum toxicokinetics of toxic low larkspur alkaloids in cattle. Animals- Five black angus steers. Procedures- Low larkspur (Delphinium andersonii) in the flowering stage was collected, dried and ground. The dried ground plant material was dosed to five Angus steers via oral gavage to represent a dose of 12 mg toxic alkaloids /kg bw. Steers were housed in metabolism crates and assessed during a 96-hour period following larkspur administration; heart rate was monitored continuously and blood samples were collected periodically for analysis of serum 16-deacetylgeyerline, methyllycaconitine, geyerline, and nudicauline and assessment of kinetic parameters. Results- Low larkspur toxic alkaloids were quickly absorbed based upon their serum maximum concentrations- Cmax being reached within 18 hours of dosing. Geyerline and nudicauline co-eluted as one peak and for toxicokinetic analysis were considered together. The elimination half-lives were 18.4 ± 4.4, 15.6 ± 1.5, and 16.5 ± 5.1 hours for 16-deacetylgeyerline, methyllycaconitine and geyerline/nudicauline respectively. There were significant differences (P < 0.05) in serum Cmax, amount absorbed, and distribution half-life values between the serum concentrations of the four alkaloids. Conclusions and Clinical Relevance- These results suggest that clinical poisoning is likely to be the most severe approximately 18 hours after exposure. Close monitoring and treatment of poisoned animals should be continued for at least 36 hours beyond initial exposure. Additionally, a withdrawal time of approximately seven days are required to clear over 99% of the toxic alkaloids from the serum of poisoned cattle that have ingested low larkspur.