There are several plants that can be poisonous to goats. However, the severity of plant poisoning depends on the quantity of the plant that was eaten, the amount of ground moisture, the health of the animal prior to consuming the toxic plant, and the size and age of the animal that consumed the plant.
Under normal circumstances, animals will not consume poisonous plants. However, there are some factors that might cause goats to eat poisonous plants. Those factors include starvation, unbalanced rations, overgrazing and drought, allowing animals to have access to yard waste or newly plowed areas where roots from toxic plants are exposed, allowing the herd to have access to dry or partially dry water hoses, incidental ingestion of toxic plants, and just plain curiosity.
Some examples of poisonous plants include azaleas, China berries, sumac, dog fennel, bracken fern, curly dock, eastern baccharis, honeysuckle, nightshade, pokeweed, red root pigweed, black cherry, Virginia creeper, and crotalaria. Please see Goat Pastures Poisonous Plants.