There is conflicting information about how toxic hemp dogbane might be. It is generally accepted that there is risk of poisoning all animal classes from grazing or feeding dried hemp dogbane. Research on poisonous plants is difficult and often depends on weather, soils, animal genetics, etc. If considering feeding a potentially poisonous plant, you should consult a veterinarian. Hemp dogbane is a weed with a vigorous root system and should be controlled in hay fields and pastures.