The effect of co-administration of death camas (Zigadenus spp.) and low larkspur (Delphinium spp.) in cattle

Authors: Welch, Kevin; Green, Benedict - Ben; Gardner, Dale; Stonecipher, Clinton - Clint; Pfister, James; Cook, Daniel

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2016
Publication Date: 1/12/2016
Publication URL: http://handle.nal.usda.gov/10113/62906
Citation: Welch, K.D., Green, B.T., Gardner, D.R., Stonecipher, C.A., Pfister, J.A., Cook, D. 2016. The effect of co-administration of death camas (Zigadenus spp.) and low larkspur (Delphinium spp.) in cattle. Toxins. doi: 10.3390/toxins8010021.

Interpretive Summary: In most rangeland settings there are multiple poisonous plants growing in the same area. Consequently, animals are potentially exposed to multiple poisonous plants containing multiple toxins. For many of the poisonous plants, basic toxicological information is available such as the LD50, the mechanism of action, and the clinical signs associated with their toxicosis. However, very rarely is there information available on the effects of animals consuming combinations of these poisonous plants. Thus, questions remain as to whether consumption of multiple poisonous plants by an animal could have an additive, synergistic, or antagonistic effect. There is potential that the toxicosis elicited by one toxin could potentiate the toxicity of another toxin such that a sub-lethal dose of each toxin, when combined, could produce a lethal result. In this regard, our previous research demonstrated that co-administration the primary toxins from death camas and low larkspur to mice had an additive effect. However, there was no additive effect when low larkspur was co-administered with death camas to sheep. The results from this study demonstrate that death camas co-treatment has no significant effect on the toxicity of low larkspur in cattle. Treatment of cattle with death camas caused clear signs of cardiovascular deficiencies, decreased heart rate and muscle fatigue. However, co-treatment with low larkspur did not exacerbate those deficiencies. The results from this study provide an increased knowledge and understanding regarding the acute toxicity of death camas in cattle. For example, the elimination half life of zygacine from the blood of cattle is approximatley 5.5 h, which indicates that after 39 h over 99% of the toxin has been eliminated. Additionally, the results of this study suggest that a toxic, but non lethal, dose of death camas is between 2-2.5 g/kg BW, on a dry weight basis, which would correspond to approximately 5-6 kg of fresh plant material for a 500 kg animal. This information will be useful in further developing livestock management recommendations for ranchers.

Technical Abstract: 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 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 death camas and low larkspur showed slightly more noticeable 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-exposure group. Overall, the results from this study suggest that co-exposure to death camas and low larkspur is not significantly more toxic to cattle than exposure to the plants individually. The results from this study increase knowledge and understanding regarding the acute toxicity of death camas and low larkspur in cattle.