Crotalaria spectabilis was introduced as a cover crop for soil improvement. Now a weed of fields, waste areas. Crotalaria sagittalis is an indigenous species.
South Eastern States and tropical areas
Horses, cattle, sheep, goats, chickens
Crotalaria flowers and seed pods
Pyrrolizidine alkaloids, the most important of which is monocrotaline. The seeds when eaten in quantity (40% of grain mix) may cause acute death. More commonly liver disease results from eating the plant or seeds.
All parts of the plant are toxic, even when it is dried. A dose of 15mg of dried plant per kilogram bodyweight over 2 weeks induces severe liver disease. Pyrrolizidine alkaloids impair cell division, affecting primarily the liver. The PA are cummulative in effect and cause severe liver fibrosis and eventual irreversible liver failure after several months.
Erect herbaceous, variably hairy plants, either annual or perennial. Leaves are simple, alternante, with finely haired surface. Flowers are showy, yellow, pea-like. Fruit is a pea-like pod, becoming black with maturity, containing glossy black heart shaped seeds.
Abnormal neurologic behavior develops (depression, aimless wandering, head pressing) once severe liver disease is present.
Red colored urine (hemoglobinuria)
Secondary photosensitization develops as a result of severe liver disease. White skinned (non-pigmented) areas become red, swollen, and painful before the skin dies and sloughs-off as if severely sun-burned.
Yellow coloration to the mucous membranes (jaundice), weight loss, diarrhea, rectal prolapse, edema of the legs, are signs of severe liver disease.
A liver biopsy to confirm the presence of megalocytosis, fibrosis and biliary hyperplasia, the classical signs of PA poisoning is the most definitive diagnostic test.
Crotalaria seeds may be a contaminant of grains.
The seeds of Crotalaria spp. remain viable for 40 years or more.
1. Stegelmeier BL et al. Pyrrolizidine alkaloid plants, metabolism and toxicity. J Natural Toxins 1999, 8: 95-116.
2. Nobre VMT et al. Acute intoxication by Crotalaria retusa in sheep. Toxicon 2005, 45:347-352.
3. Williams MC, Molyneux RJ. Occurrence, Concentration, and Toxicity of Pyrrolizidine Alkaloids in Crotalaria Seeds. Weed Science 1987: 35, 476-481.
4. Allen JR, Childs GR, Cravens WW. Crotalaria spectabilis toxicity in chickens. Proceedings of the Society for Experimental Biology and Medicine 1960:104, 434-436.
5. John CP, Sangster LT, Jones OH. Crotalaria spectablis poisoning in swine. J Am Vet Med Assoc 1974; 165: 633-638