Microhistological analysis of sheep gastro-intestinal content to confirm poisonous plant ingestion

Abstract

The epidermal remains of 4 poisonous plant species that produce acute intoxication in ruminants were quantified by microhistological analysis in the gastro-intestinal content of sheep experimentally poisoned. These species were 'romerillo' or 'mio mio' (Baccharis coridifolia DC); 'duraznillo negro' (Cestrum parqui L'Hérit.); 'poison hemlock' (Conium maculatum L.), and 'sunchillo' (Wedelia glauca (Ort.) Hoff.). All of these species produce important economic losses of livestock in the Flooding Pampa, Buenos Aires, Argentina. The plants used for intoxication were at the vegetative stage of growth. Results indicate that the microhistological technique can be used to confirm the diagnosis of ruminant intoxication by duraznillo negro, romerillo, and sunchillo, but not by poison hemlock because digestion degrades its fragments beyond recognition. It would be convenient to sample the final sections of the digestive tract to confirm romerillo and sunchillo ingestion, because their fragments tend to concentrate there. The uniformity of duraznillo negro fragment distribution would allow identification of this species from any section of the digestive tract. However, the considerable variability in fragment distribution found among animals poisoned with the same plant species makes it necessary to sample more than 1 digestive region if only 1 animal is available for necropsy.