Tansy ragwort (Senecio jacobaea) is common on Western rangeland and is toxic both fresh and dry. Being unpalatable, it is only consumed when other forages are unavailable or it contaminates harvested forage. Its pyrrolizidine alkaloids are toxic to liver cells and cause chronic cirrhosis-like injury. Signs of toxicity can appear months after the plant was ingested and include lethargy, poor appetite, weakness, nervousness, colic, aimless wandering, blindness, abdominal distension, incoordination, jaundice, coma and death due to liver failure. Diagnosis can be made via liver biopsy or liver function tests.
Nightshades (Solanum species) are many; this genus includes many potentially-poisonous members such as potato, horse nettle and many nightshades. Tomatoes are closely-related to this genus and contain the same toxic agent. Signs of poisoning with tomato vines, green tomatoes, green potato skins, potato sprouts and parts of other plants in the Solanum genus are due to the toxic alkaloid called solanine. These signs can include lethargy, drooling, difficulty breathing, tremors, colic, vomiting, diarrhea or constipation, weakness, coma, widely-dilated pupils, paralysis, convulsions, coma and death.
Brassica species and other members of the mustard family (kale, cabbage, rape, turnips, etc.) contain toxic glucosinolates in fresh and dry seeds and vegetative parts. Some species can cause goiter; others contain a toxin that causes hemolytic anemia. Most cases of poisoning involve cattle. Signs include decreased appetite, drooling, reduced rate of gain, anemia, weakness, severe vomiting and diarrhea, staggering, photosensitization, paralysis, abortion, collapse and death. New cultivars have been developed with greatly-reduced levels of toxins and are generally safe to feed to livestock.
Prickly lettuce (Lactuca scariola) can cause pulmonary emphysema in cattle. Young plants are most toxic; mature and dried plants appear to be non-toxic. Also known as China lettuce, this plant can also accumulate nitrates. Cases of poisoning are typically seen in the spring and after fall re-growth. Signs of toxicity include audibly-labored breathing and weakness. On autopsy, lungs are markedly emphysematous (bulging with trapped air).