Vicia villosa

Abstract

DISTRIBUTION: Imported plant. Cultivated as pasture in the Western and Eastern Cape and Northern province.BOTANICAL DESCRIPTION: General: Grows up to 1 m high. Generally a good fodder, though various toxic syndromes have been associated with it. Leaves: Compound leaf with a characteristic tendril at the end of the midrib which twines around other plant material. Flowers: Purple blue pea-like flowers in an erect raceme. Spring - Summer. Fruit: Small erect podsTOXIC PRINCIPLE: Unknown. Unable to reproduce experimentally. Only circumstantial evidence.SYSTEMS AFFECTED: Skin and appendages.CLINICAL SIGNS: • Problem in cattle. • Occurs in adult cattle (more than 3 years old). • Seen in dark breeds (Holstein-Friesians, Aberdeen Angus) which graze for a relative long period (more than 1 month) on green pasture and consume large quantities. • Latent period 2 - 6 weeks. • Severe dermatitis and pruritus noticed initially. • Roughened coats, alopecia. • Cracks develop in the skin, serum oozes out, crust formation, tissue under crusts are severely inflamed. • Later, skin becomes unpliable, hard. • Severe exudative to ulcerative dermatitis. • Pigmented and non-pigmented skin are affected. (Compare with photosensitivity) • Mucous membranes affected - conjunctivitis, salivation, mucopurulent nasal discharge. • Coughing, dyspnoea. • Severe diarrhoea - even haemorrhagic. • Drop in condition, emaciation, dehydration, drop in milk production. • Sick for one week, may take 1 month before they die. • Older animals more severely affected. • Up to 35% morbidity and high mortality.NECROPSY: HISTOPATHOLOGY: 1. Granulomatous lesions in various organs. - Infiltration of lymphocytes, monocytes and eosinophils in lesion. - Granulomas in kidney, spleen, liver, myocardium and skin. 2. Skin: - multifocal, - ulcerative dermatitis with hyperkeratosis, - oedema, - cell infiltration and fibrosis.TREATMENT: Antibiotics, fluid and electrolyte replacement, local skin treatment.