If one plant toxin is harmful to livestock, what about two?

When livestock are poisoned by plants in a range setting, there is normally more than one poisonous plant in that area. Additionally, many plants contain more than one compound that is toxic to livestock. Frequently, much is known regarding the toxicity of the individual plants and their individual toxins; however, little is known regarding the effect of coexposure to multiple toxic plants or even the effect of multiple toxins from an individual plant. This review discusses some basic principles of mixture toxicology with a focus on recent research that examined the effect of co-administering multiple plant toxins from the same plant and the effect of co-administration of two different poisonous plants, each with different types of toxins. As combined intoxications are likely common, this information will be useful in further developing management recommendations for ranchers and in designing additional experiments to study the toxicity of multiple poisonous plants to livestock.