Lippia rhemannii

Abstract

DISTRIBUTION: Grass- and bushveld, mainly Pretoria/Magaliesburg area. Botanical description: General: A shrub, 0,5 - 1 m high, with many branches spreading from ground level. All parts strongly aromatic, smelling like lemon peel. Young stems quadrangular, becoming more round with age - they are slightly hairy and rough to the touch. Leaves: The leaves are opposite, with toothed margins and rough surfaces. Flowers: The small, yellowish white flowers are grouped in compact round flower heads, which are borne on long stalks (±5 cm) in the leaf axils. Spring - summer. Fruit: The fruit is small and two-chambered with one seed in each chamber.

TOXIC PRINCIPLE: • Icterogenins and rhemannic acid are also pentacyclic, triterpene acids like lantadene. • The toxicity is very similar to that of Lantana camara. Mechanism of action: • Alters permeability of liver cell membranes and leads to intrahepatic cholestasis with relatively little damage to liver cells. • Also paralyses smooth muscle of gall bladder - can’t contract and bile accumulation may cause erosion. • Phylloerythrin concentration increases in the circulation.

SYNDROMES: Hepatogenous photosensitivity primarily due to liver parenchymal damage.

SYSTEMS AFFECTED: Liver.

CLINICAL SIGNS: • Clinical signs very similar to Lantanta camara poisoning. • Mainly a cattle problem. Sheep are also susceptible, but seldom eat it. Goats may eat it. • Secondary photosensitivity - hairless areas i.e. muzzle and perineal area, also unpigmented areas. • Marked icterus. • Rumen stasis, constipation - may have diarrhoea.

NECROPSY: Macroscopical findings: 1. Secondary photosensitivity skin lesions 2. Yellow to orange brown liver with enormously enlarged gall bladder with oedematous wall containing straw-coloured to dark green bile. 3. Nephrosis 4. Impaction of caecum and colon.

HISTOPATHOLOGY: • Relatively mild changes in liver and kidney.

TREATMENT: • Can try choleretics, i.e. clanobutin • Antihistamines • Antibiotics • Place in shade • Dose activated charcoal • Diet low in chlorophyll (good quality hay) • Skin protectant creams.