Panicum species

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Botha, C.J. (Christoffel Jacobus)
Venter, Elna

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Abstract

DISTRIBUTION: Grows in fertile, damp soil, usually in the shade.
BOTANICAL DESCRIPTION: General: Annual or perennial tufted grass species growing from rhizomes. Leaves: Leaf sheath is often hairy and leaf blades are rolled. Flowers: Inflorescence is an open panicle and often flushed with purple when growing in direct sunlight. September - March.
TOXIC PRINCIPLE: • Similar to Geeldikkop. • Toxic principle: Steroidal saponins.
MECHANISM OF ACTION: • Hydrolysis of a steroidal saponin to diosgenin with subsequent hydrogenation, reduction and epimerisation, which occurs in the rumen. • Epismilagenin and episarsasapogenin amongst others, are formed, absorbed and conjugated with glucuronic acid in the liver to be excreted via the bile. • However, the epismilagenin and episarsasapogenin glucuronides bind to Ca2+ to form an insoluble salt, which precipitates to form biliary crystals which obstruct the bile ducts.
SYNDROMES: Dikoor.
SYSTEMS AFFECTED: Liver.
CLINICAL SIGNS: Dikoor – similar to geeldikkop – distribution Free State and Highveld. Sheep condition mainly. Usually milder disease (probably due to farming practice – detected earlier and kept in shade etc.).
NECROPSY: Identical to Geeldikkop - Clefts, etc. identical Macroscopical findings: • Icterus and photosensitivity. • Liver - enlarged khaki to yellow-brown. • Chalky white sediment in bile ducts and gall bladder. • Later small pits on surface although morphology never distorted as in F.E. • Kidneys swollen and light in colour, with small green spots distributed through cortex.
HISTOPATHOLOGY: • Accumulation of crystalloid material in portal and intra- and extrahepatic bile ducts leading to partial or complete occlusion and concentric, lammellar periductal fibrosis. • Plate-like structures seen on section as clefts and on scanning EM as rose- like structures and/or debri in greater ducts. • Other pathological changes are present but are mostly secondary to this.
TREATMENT: Keep in shade. Diet low in chorophyll. Antihistamines. Corticosteroids. Cholagogues. Liver supportive treatment. Valuable animals – barrier creams and tattoo ink will protect from sunburn.

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Colour photos. Final web-ready size: JPEG. Photo 1: 12.9 kb, 96 ppi; Photo 2: 23.7 kb, 72 ppi; Photo 3: 102 kb, 72 ppi; Photo 4: 26.5 kb, 96 ppi. Original TIFF file housed at the Dept. of Paraclinical Sciences, Section Pharmacology and Toxicology, University of Pretoria.

Keywords

Plant poisoning, Toxicology, Plant poisoning in animals, Poisonous plants, Dikoor, Saponins

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Citation

Botha, CJ & Venter, E 2002, 'Plants poisonous to livestock Southern Africa (CD-ROM)' University of Pretoria, Faculty of Veterinary Science, Dept. of Paraclinical Sciences, Section Pharmacology and Toxicology, Pretoria, South Africa.