A toxicokinetic comparison of two species of low larkspur (Delphinium spp.) in cattle

Low larkspurs have different toxic potentials to livestock due to variation in the individual alkaloids present in the plants. Two species, Delphinium nuttallianum and Delphinium andersonii were dosed to 10 Holstein steers at 10 mg and 12 mg toxic alkaloids/kg, respectively. Blood samples were collected periodically for 96 h, analyzed for serum alkaloid concentrations and toxicokinetic parameters calculated for 16-deacetylgeyerline, 14-deacetylnudicauline, methyllycaconitine and geyerline/nudicauline which co-eluted in the serum analysis. The maximum serum alkaloid concentrations and area under the curve values for 16-deacetylgeyerline and geyerline/nudicauline were significantly different between the two groups due to the concentrations of the alkaloids in each larkspur species. The alkaloid elimination half-lives were similar for the two larkspur species. These results suggest the elimination rates of norditerpene alkaloids from different larkspur species in cattle are similar regardless of plant alkaloid composition. The determining factor for larkspur toxicity is the individual alkaloid composition of the plant.