Thesium species

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Botha, C.J. (Christoffel Jacobus)
Venter, Elna

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Abstract

DISTRIBUTION: These plants grow in the arid to semi-arid areas of southern Africa; in open plains, seasonally dry watercourses and on hills.
BOTANICAL DESCRIPTION: General: These small, woody perennial shrubs (up to 1,5 m) are in fact semi-root parasites. Leaves: The many thin, woody upright stems and branches of T. namaquense are green to yellow-green and virtually leafless except to the expert eye. Those of T. lineatum are grey-green or blue-green. Flowers: The flowers are inconspicuous, pale yellowish in colour and borne at the end of the branches or in the axils of the minute leaves. Early winter - spring. Fruit: Very small, spherical, with longitudinal ridges.
TOXIC PRINCIPLE: Bufadienolide, a cardiac glycoside.
SYNDROME: Non-cumulative bufadienolides.
SYSTEMS AFFECTED: Cardiovascular system.
CLINICAL SIGNS: • A period of laboured, shallow panting • Diarrhoea • Loss of muscular control • In some cases death may be quite sudden.
NECROPSY: Macroscopical findings: • Not specific - rather negative • Subepi- and endocardial haemorrhages • Lung oedema, congestion, emphysema • Ruminal atony and enteritis - even haemorrhagic • Leaves present in rumen.
HISTOPATHOLOGY: In more chronic cases small foci of degeneration of cardiac musculature are seen occasionally.
TREATMENT: • Activated charcoal is very effective. • Dose 2g/kg. • Large dose is essential. • Adsorption and fixation of excess in rumen. • Even retro-diffusion back from plasma. • Minimize stress to prevent catecholamine release. Additional treatment for valuable animals: 1. Lignocaine. 2. ß-blocking agents 3. ACP: Tranquillizer (multipotent blocker) 4. Atropine (if AV-block is present).

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Colour photos. Final web-ready size: JPEG. Photo 1: 7.33 kb, 72 ppi; Photo 2: 31.1 kb, 150 ppi; Photo 3: 42.9 kb, 96 ppi. Original TIFF file housed at the Dept. of Paraclinical Sciences, Section Pharmacology and Toxicology, University of Pretoria.

Keywords

Plant poisoning, Toxicology, Plant poisoning in animals, Poisonous plants, Bufadienolides, Cardiac glycosides

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Citation

Botha, CJ & Venter, E 2002, 'Plants poisonous to livestock Southern Africa (CD-ROM)' University of Pretoria, Faculty of Veterinary Science, Dept. of Paraclinical Sciences, Section Pharmacology and Toxicology, Pretoria, South Africa.