Hairy Vetch

Vicia villosa

Fabaceae (Legume family)


Description

Hairy vetch is an annual or biennial spreading herb with climbing stems growing up to 3 feet long. The leaves have long, soft hairs with 10 to 20 leaflets borne opposite each other and tendrils at the end. The flowers, borne in a dense one-sided spike, are violet and white to rose colored. The oblong pod has a beak-shaped tip, grows up to 1.25 inches long and opens at maturity.


Habitat

Hairy vetch has been widely introduced and cultivated with cereal grains as a cool-season forage in the eastern third of Texas. It has escaped in many areas, and dense stands are found along roadsides and in pastures where it has been allowed to seed. A native species, Vicia leavenworthii, which extends west to Schleicher County, is associated with cases of vetch poisoning in rare instances where there was adequate fall and winter rainfall for abundant growth.


Toxic Agent

Neither the toxic agent nor the specific conditions in which poisoning develops are known. Poisoning invariably involves animals with black pigmented skin (Angus, Angus cross or Holstein cattle; black horses). Poisoning usually occurs after the plants begin to flower, but some cases have occurred in Central Texas when the plants were in the seedling stage with runners no more than 8 inches long. Years of uneventful grazing of vetch can pass between poisoning episodes.


Signs of Livestock Ingestion

The first clinical signs of affected animals appear similar to photosensitization, except that the lesions are on black skin. Clinical signs may include: Inflamed skin (head, neck and tailhead); Thickening of skin with granular tumors; Matting of hair and sloughing of skin; Diarrhea; Anorexia; Loss of weight; Death.

The death rate of affected animals is high. They often die from kidney failure, as granulomas grow in the various internal organs, including the kidneys.


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