Merwilla plumbea

Abstract

DISTRIBUTION: • Mainly found in Kwazulu-Natal • Very variable • In damp grassland, cliffs and rocky slopes.

BOTANICAL DESCRIPTION: General: Up to 1m high. Grows solitary or in colonies. The papery, purplish brown bulbs grow half above the ground. Leaves: 6 - 8. Usually appear after the flowers. Grey-green, erect, ±500mm. Flowers: Inflorescence ±300 x 100 mm. Flowers are pale to deep purplish blue on long slender stalks. Spring.

TOXIC PRINCIPLE: Bufadienolide cardiac glycosides.

SYNDROME: Non-cumulative bufadienolides.

SYSTEMS AFFECTED: Cardiovascular system.

CLINICAL SIGNS: • Fatally poisoned stock usually dies 24 to 48 hours. • Non-fatally poisoned stock generally recovers within three to four days.

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.