PESSOA, C. R. M.; http://lattes.cnpq.br/0453622502731275; PESSOA, Clarice Ricardo de Macêdo.
Resumo:
The papers that comprises this thesis derive from studies of plant poisoning, conducted by a
research group on toxic plants from the National Institute of Science and Technology for
Control of Poisonous for Plants, based in Veterinary Hospital, Federal University of Campina
Grande in Patos, Paraíba. The first paper is a review of the economic importance,
epidemiology and control of plant poisonings in Brazil. The expected annual losses by animal
deaths caused by toxic plants was estimated in 820,761 to 1,755,763 cattle, 399,800 to
445,309 sheep, 52,675 to 63,292 goats, and 38,559 horses. Most of the losses are caused by
Palicourea marcgravii, Amorimia rigida, Senecio spp., Pteridium aquilinum, Cestrum
leavigatum, and Ateleia glazioviana in cattle, Brachiaria spp in cattle and sheep, and Ipomoea
asarifolia and Nierembergia veitchii in sheep, plants containing swainsonine (Ipomoea
carnea, Turbina cordata and Sida carpinifolia) in goats and Brachiaria humidicola and
Crotalaria retusa in horses. The main epidemiological factors that determine plant poisonings
include palatability, hunger, thirst, social facilitation, unaware of the plant, access to toxic
plants, toxic dose, ingestion period, variations in toxicity and resistance to poisoning of
animals. The methods of control and prevention recently developed in Brazil include:
biological control, conditioned food aversion, using non-toxic varieties of forages, use of
animals resistant to poisoning, and techniques of inducing resistance. The second paper was
the result of a research project that aimed to prove the hypothesis that, in horses, the
dehydropirrolizidine alkaloid monocrotaline present in the seeds of Crotalaria retusa only
produces liver injury, while dehydropirrolizidine alkaloids present in the seeds of Crotalaria
juncea (isohemijunceines, trichodesmine and junceine) produce lung injury. The results
confirmed the hypothesis that while monocrotaline cause liver injury (centrilobular necrosis)
alkaloids contained in C. juncea cause pulmonary lesions (proliferation of Clara cells and
fibrosis). The third paper reports the clinical signs, pathology and control measures of
Marsdenia spp. poisoning in ruminants the semiarid region of northeastern Brazil. The
poisoning was characterized by nervous signs, with non significant histological lesions.
Nervous signs similar to those observed in the spontaneous poisoning were induced
experimentally by administration of roots of M. hilariana for goats and leaves and roots of
M. megalantha for sheep.