Fadagio homblei

Abstract

DISTRIBUTION: • Bushveld and rocky ridges, mainly in sandy soils (white, grey or pale-red soils). • To the North and East of Pretoria, also common in parts of Gauteng, Limpopo and Swaziland.

BOTANICAL DESCRIPTION: General: A perennial herbaceous shrublet with many erect, unbranched annual stems about 50 cm high. These arise from a thickened, erect, underground stem and die off in winter. Leaves: The stalkless, shiny green leaves are greyish white felted below. Produced at approximately evenly spaced intervals up the stem in whorls of 3 to 5. Flowers: Star-shaped, yellowish-green flowers with 5 petals clustered in the axils of the leaves. Fragrant. Spring. Fruit: Fleshy round berries which are green at first, shiny black when ripe. A single seed in each of its three chambers.

TOXIC PRINCIPLE: • A water-soluble polyamine called pavettamine. • Has a delayed effect on the heart. • This toxin is pH-labile and will be destroyed at pH < 2,5. • This could explain why only ruminants are susceptible (Rumen pH = 6,8). • Only very young sprouting plants are toxic.

SYNDROME: Gousiekte

SYSTEMS AFFECTED: Cardiovascular system.

CLINICAL SIGNS: Mechanism of action: The toxin inhibits synthesis of new myocardial protein, especially myosin.

• After ingestion of a lethal dose of the plants, a characteristic latent period of 6 - 8 weeks of apparent normality follows before the animals suddenly die.

• The majority of animals typically drop dead, usually after being frightened, handled or chased, although some may die without any stressful event occurring.

• In a few cases congestive heart failure such as weakness, panting, respiratory distress and anasarca, particularly of the head, are present.

NECROPSY: Macroscopical findings: Signs of heart failure: • Lung oedema • Hydrothorax • Hydropericardium although some cases may not show any macroscopic changes. Irregular areas of pallor (greyish areas) may be seen, particularly in the endocardium.

HISTOPATHOLOGY: • A multifocal to diffuse subendocardial replacement fibrosis accompanied by a round cell infiltration, predominantly in the apex, left ventricular wall and inter- ventricular septum. • Focal to diffuse degeneration and/or necrosis of myofibres. • Hypertrophy or even atrophy of myocardial fibres.

TREATMENT: •No specific treatment, only symptomatic and supportive •Avoid unnecessary stressful situations