Cotula nigellifolia

Abstract

DISTRIBUTION: It grows in damp places, near or even in water, and prefers shady areas.

BOTANICAL DESCRIPTION: General: An indigenous perennial, herbaceous weed. More or less spreading, but some stems can grow up to a height of 30 to 60 cm. The soft stems are greyish green, but become reddish-purple at times. Leaves: The simple greyish green leaves are deeply incised. Flowers: The inflorescence is a daisy-like flower borne on a thin green stalk with white outer flowers and yellow disc-florets. September - April. Fruit: The seeds are small and oblong.

TOXIC PRINCIPLE: Unknown neurotoxin – causes encephalitis.

SYSTEMS AFFECTED: Central nervous system.

CLINICAL SIGNS: Only a problem with cattle especially in KwaZulu-Natal and the Eastern Cape. Sheep and horses not susceptible. • CNS suppression characterized by: - apathy, - very tame, - easy handling, - aimless wandering and - apparent blindness • Incoordination, which can progress to paresis and eventually paralysis. - Uncertain when walking, knuckling over • Pushing syndrome - can only lean against or actively push against firm objects • Loss of weight (chronic cases) because they don’t eat or drink.

NECROPSY: Macroscopical findings: • Nothing obvious. • Only signs of trauma and weight loss.

HISTOPATHOLOGY: Encephalitis characterized by perivascular gliosis and lymphocyte infiltration in white matter of the brain and status spongiosus.

DIAGNOSIS: • Histopathology changes are characteristic • Typical clinical signs.

TREATMENT: • None • Keep the animal away from infected areas in times of food scarcity.