Botanical Name

Crotalaria spp.

Synonyms

No documentation

Family

Leguminosae

Vernacular Names

Description

The genus Crotalaria is a member of the Leguminosae family.The genus contains a number of species that are toxic to livestock such as C. sagittalis, C. spectabilis, C. retusa, C. mucronata var. giant-striate, C. inacna, C. rotundifolia, C. burkeana, C. juncea, C. dura, C. equorum, and C. globifera.  They are coarse herbaceous plants with stout branches and are either annuals or short-lived perennials. The leaves are variable ranging from simple to trifoliate; stipules may be absent or present. The calyces are unequal free or fused lobes; and campanulater. The corollas are butterfly shapes. The flowers are usually yellow or olive green in colour. The legumes are globose to oblong; swollen to inflated. The seeds may be single to many; usually cordate to oblong-reniform. The seeds in the persistent dried fruit cause a rattling noise when the fruit is shaken [1] [3] [4].

Distribution

Crotalaria spp. are widely distributed and are considered a nuisance to livestock farmers. They occur in West Indies and all parts of North America, Africa and Asia [3].

Plant Use

Some Crotalaria species are showy and had been grown as ornamentals. They are also cultivated for erosion control and green manure in India, South-eastern United State, and tropical America [6].

Toxic Parts

Whole plant is poisonous [3].

Toxin

The major toxin in Crotalaria spp. are the pyrrolizidine alkaloids and of particular monocrotaline. It is actually the dehydro products of monocrotaline, that is the primary source of the toxicity. The toxin is cumulative. It produces damage in the form of thrombosis in the liver veins leading to veno-occlusive hepatitis with subsequent cirrhosis. Monocrotaline acts on the DNA of the hepatocytes causing constriction of the lumen in the medium and small veins of the hepatic portal system. At the same time it is also a non-competitive inhibitor of respiratory chain complex I NADH oxidase activity seen in rat liver mitochondria. The compound also causes significant extrahepatic effects including pneumotoxicity and nephrotoxicity. Pneumotoxicity causes mast cells in the lungs to release 5-hydroxytryptamine which is responsible for pulmonary vascular lesions [1] [2] [4] [5].

Risk Management

Cases of poisoning by plants containing pyrrolizidine alkaloids is relatively rare as compared to animals. The reported case of poisoning in children is seen amongst West Indian communities where “bush tea” made from leaves of Crotalaria sp. are given. Such practices should be stopped to avoid occurrences of hepatic veno-occlusive disease [1] [2] [3] [4] [5].

Clinical Findings

In human beings, substantial short-term exposure to Crotalaria sp. toxins may cause acute hepatitis. In chronic exposure to lower levels may cause hepatic veno-occlusive disease (Budd-Chiari Syndrome) and in some cases pulmonary hypertension [3]. 

Symptoms seen in livestock vary according to the animal. In horses the disease is called River Bottom disease where the symptoms are basically neurological i.e. weakness, stupor, incoordination, aimless walking, delirium, excitement, and apparent blindness. There is emaciation and icterus which finally culminated in death. In cattle the clinical presentation are of three types i.e. acute, intermediate and chronic. Symptoms include weakness, emaciation, incoordination, constipation and diarrhoea in intermediate cases. In chronic cases there is loss of appetite, poor condition, tenesmus, nervousness, excitability, blood in faeces, prostration, bloody nasal discharge and finally death. In chicken there are characteristic discoloration of the coomb, severe greenish-yellow diarrhoea and depression with ruffled feathers [1] [2] [3].

Management

Treatment is generally supportive with parenteral fluids and a low protein diet to reduce the nitrogenous load to the liver [4]. 

The best treatment is prevention by vigilance. In livestock, copper sulphate and ferric ammonium citrate have been reported to bring about dramatic recovery [2].

References

1. Vijay KM. Veterinary toxicology. New Delhi: New India Publishing; 2009. p. 218-219.
2. Nellis DW. Poisonous plants and animals of Florida and the Caribbean. Sarasota, Florida: Pineapple Press; 1997. p. 197-198.
3. Nelson LS, Shih RD, Balick MJ. Handbook of poisonous and injurious plants. Berlin: Springer-Verlag; 2007. p. 139-140.
4. Burrows GE, Tyrl RJ. Toxic plants of North America. Ames, Iowa: John Wiley & Sons; 2013. p. 535-541.
5. Barceloux DG. Medical toxicology of natural substances: foods, fungi, medicinal herbs, plants and venomous animals. Hoboken, New Jersey: John Wiley & Sons; 2012. p. 449-457.
6. Roecklein JC, Leung PS. A profile of economic plants. New Brunswick: Transaction Inc.; 1987. p. 79.