Larkspur Poisoning of Cattle: Plant and Animal Factors that Influence Plant Toxicity (original) (raw)
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A toxicokinetic comparison of two species of low larkspur (Delphinium spp.) in cattle
Research in Veterinary Science, 2013
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 10mg 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.
American Journal of Veterinary Research, 2010
Objective-To determine the contribution of 7,8methylenedioxylycoctonine (MDL)type alkaloids to the toxic effects of tall larkspur (Delphinium spp) consumption in cattle. Animals-Sixteen 2yearold Angus steers. Procedures-Plant material from 3 populations of tall larkspur that contained different con centration ratios of MDLtypetoA/(methylsuccinimido) anthranoyllycoctonine (MSAL)type alkaloids was collected, dried, and finely ground. For each plant population, a dose of ground plant material that would elicit similar clinical signs of toxicosis in cattle after oral administra tion was determined on the basis of the plants' MSALtype alkaloid concentration. Cattle were treated via oral gavage with single doses of ground plant material from each of the 3 populations of tall larkspur; each animal underwent 1 to 3 singledose treatments (> 21day interval between treatments). Heart rate was recorded immediately before (baseline) and 24 hours after each larkspur treatment. Results-Tall larkspur populations with a lower MDLtypetoMSALtype alkaloid concentra tion ratio required a greater amount of MSALtype alkaloids to cause the expected clinical signs of toxicosis (including increased heart rate) in cattle.
Journal of Animal Science, 2019
Cattle losses from larkspur (Delphinium spp.) toxicity are a long-term challenge on the rangelands of western North America. In addition to animal factors that affect livestock poisonings, plant alkaloid composition (chemotype) affects the intoxication of cattle because some chemotypes are significantly more toxic. Differences in larkspur chemotype toxicity are due to the ratios of N-(methylsuccinimido) anthranoyllycoctonine (MSAL)-type alkaloids to non-MSAL-type alkaloids and the concentrations of those alkaloids in the plant material. The objective of this study was to compare the responses of 6 Angus heifers to 6 chemotypes of larkspur using a Latin square study design. These Angus heifers from the USDA-ARS, Meat Animal Research Center in Clay Center, NE, were chosen for this research because they are the most larkspur-susceptible cattle observed to date. The 6 heifers were given an oral dose of dried ground larkspur and tested for muscle weakness with an exercise test (i.e., walk time). The 6 chemotypes of larkspur had non-MSAL to MSAL-type alkaloid ratios ranging from 1.4:1 to 6:1 and were administered at an oral dose of 7.5 mg/kg MSAL-type alkaloids BW. There was a treatment effect due to larkspur chemotype (P < 0.0001), and period effects were not significant (P = 0.6). There were also significant correlations between the length of time walking on a dirt track at 5 to 6 km/h, and total alkaloid dose (r = −0.92, P = 0.0045) and alkaloid ratio (r = −0.81, P = 0.0258). Serum alkaloid concentrations at 24 h after dosing were representative of the relative abundance of the alkaloid in the plant material. Results from this work suggest that total alkaloid concentrations in combination with alkaloid ratios can be used together to accurately predict the plant risk component of larkspur poisoning to grazing cattle. Animal factors such as cattle age, breed, and sex must also be considered to comprehensively manage larkspur risk.
Sex-dependent differences for larkspur (Delphinium barbeyi) toxicosis in yearling Angus cattle1
Journal of Animal Science, 2019
Larkspur (Delphinium spp.) poisoning is a long-term problem for cattle grazing on rangelands of western North America. Results from preliminary experiments have suggested that differences in larkspur toxicity may exist between heifers and bulls. The objective of this study was to compare the physiological responses of yearling Angus heifers, steers, and bulls with a standardized dose of Delphinium barbeyi and to test the hypothesis that the response is sex dependent. Clinical signs of intoxication, including muscle coordination and function, were measured 24 h after oral dosing with larkspur by walking the cattle at a pace of 5 to 6 km h −1 for up to 40 min on an oval dirt track. Due to the experimental methods used, the variation in susceptibility to larkspur was not quantifiable for walking times of 0 or 40 min or more. Larkspur susceptible animals that were not able to walk (0 min; 36% of the animals) or larkspur resistant animals that walked the entire test period of 40 min (9% of the animals) resulted in censored or truncated data. The statistical methods (censReg and lmec) were used to adjust for data truncation or censoring. The heifers were only able to walk −8.9 ± 3.9 min (65.5% censored on the left) compared with 13.2 ± 3.7 min for bulls and 15.9 ± 2.7 min for steers. When heifers were compared with bulls and steers together, heifers walked 23.4 ± 4.5 min less (P < 0.0001). Serum alkaloid concentrations were measured immediately before walking, and deltaline concentrations averaged 266 ± 28, 131 ± 20, and 219 ± 28 ng mL −1 for all heifers, steers, and bulls, respectively, and serum methyllycaconitine concentrations averaged 660 ± 46, 397 ± 32, and 612 ± 34 ng mL −1 for all heifers, steers, and bulls, respectively. The relative risk of a zero walk time for yearling heifers is 330% that of yearling bulls (P = 0.0008). These results suggest that yearling Angus heifers are more susceptible to larkspur intoxication and, when possible, heifers should be kept from grazing larkspur-infested rangelands as a simple management tool to reduce the risk of fatal poisoning.
Journal of Animal Science, 2012
Larkspur plants contain numerous norditerpenoid alkaloids, which include the 7,8-methylenedioxylycoctonine (MDL)-type alkaloids and the N-(methylsuccinimido)anthranoyllycoctonine (MSAL)type alkaloids. The MSAL-type alkaloids are generally much more toxic (typically >20 times). Toxicity of many tall larkspurs, such as Delphinium barbeyi, has been attributed to its large concentration of MSALtype alkaloids, including methyllycaconitine (MLA). However, the norditerpenoid alkaloids found in the greatest concentrations in most D. barbeyi populations are either deltaline or 14-O-acetyldictyocarpine (14-OAD), both less toxic MDL-type alkaloids. Although the individual toxicities of MLA, 14-OAD, and deltaline have been determined, the impact (additive or antagonistic) that large concentrations of deltaline or 14-OAD in the plant have on the toxicity of MLA is unknown. Consequently, the effect of MDL-type alkaloids on the toxicity of MLA was compared by using median lethal dose (LD 50 ) and toxicokinetic profiles of the brain and muscle from mice receiving i.v. administration of these alkaloids, individually or in combination, at ratios of 1:1, 1:5, and 1:25 MLA to MDL-type alkaloids. The LD 50 for MLA alone was 4.4 ± 0.7 mg/ kg of BW, whereas the coadministration of MLA and deltaline at 1:1, 1:5, and 1:25 resulted in an LD 50 of 2.7, 2.5, and 1.9 mg/kg of BW, respectively. Similarly, the coadministration of MLA and 14-OAD at 1:1, 1:5, and 1:25 resulted in an LD 50 of 3.1, 2.2, and 1.5 mg/ kg of BW, respectively. Coadministration of mixtures did not result in increased MLA bioavailability or alterations in clearance from the brain and muscle. Consequently, the increased toxicity of the mixtures was not a result of increased MLA bioavailability (based on the maximum concentrations observed) or alterations in MLA clearance from the brain and muscle, because these were unchanged. These results demonstrate that MDL-type alkaloids have an additive effect on MLA toxicity in mice and may also play a role in the overall toxicity of tall larkspur plants in cattle.
2020
Larkspurs (Delphinium spp.) are toxic native plants on foothill and mountain rangelands in western North America, which poison cattle grazing on those rangelands. The purpose of this study was to examine in a laboratory setting, the subclinical effects of larkspur intake and toxicosis, by allowing larkspur susceptible and resistant cattle to self-select the amount of larkspur consumed in pellet form. We hypothesized that there would be differences in short term (9-11 day) pellet consumption between susceptible and resistant animals. Two trials were completed, each with larkspur resistant and susceptible Angus steers, and larkspuralfalfa pellets at a 12% and 6% larkspur for trial 1 and trial 2, respectively. There were no differences in pellet consumption between the two groups in either trial. The cattle were averted to the 12% larkspur-containing pellet in trial 1. During trial 2, the susceptible and resistant steers differed in serum concentrations of methyllycaconitine (MLA) on days 9 to 12 but did not have significantly different exercise times (38.0 ± 3 min and 27.2 ± 6.5 min for resistant and susceptible steers, respectively). Larkspur alkaloids were potent aversive agents in cattle when fed as a 12% larkspur-containing pellet. The lack of differences in responses between susceptible and resistant cattle were attributed to the development of pharmacodynamic tolerance to larkspur alkaloids by the actions of larkspur alkaloids at nicotinic acetylcholine receptors.
Toxins, 2016
In many rangeland settings, there is more than one potential poisonous plant. Two poisonous plants that are often found growing simultaneously in the same location in North American rangelands are death camas (Zigadenus spp.) and low larkspur (Delphinium spp.). The objective of this study was to determine if co-administration of death camas would exacerbate the toxicity of low larkspur in cattle. Cattle dosed with 2.0 g of death camas/kg BW showed slight frothing and lethargy, whereas cattle dosed with both death camas and low larkspur showed increased clinical signs of poisoning. Although qualitative differences in clinical signs of intoxication in cattle co-treated with death camas and low larkspur were observed, there were not any significant quantitative differences in heart rate or exercise-induced muscle fatigue. Co-treatment with death camas and low larkspur did not affect the serum zygacine kinetics, however, there was a difference in the larkspur alkaloid kinetics in the co...