Thesium species

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).