Malformações em pequenos ruminantes.

Abstract

This thesis includes a review and two papers. The first chapter is a review about general principles of teratology and epidemiology, diagnosis, clinical signs and pathology of malformations in small ruminants. The second chapter is a paper that studied the teratogenicity of Mimosa tenuiflora. Fifteen sheep, divided into two groups, were introduced into an area invaded by the plant. Group 1 consisted of six pregnant ewes that were introduced into the experimental area 20 days after mating. Group 2 consisted of nine non pregnant sheep and a ram introduced into the area at the start of the experiment. Every 15 days each sheep was examined by ultrasound to control pregnancy. In Group 1, three sheep aborted single fetuses without malformations. One sheep delivered two lambs, one with hyperflexion of the proximal inter-phalangeal joint of the right forelimb and another without malformations. Another sheep delivered a lamb with a hyperflexion of both hindlimbs in the region of the tarsal-metatarsal joint. Only one sheep delivered a normal lamb. In Group 2, one sheep aborted a fetus without malformations and five delivered normal lambs. Three sheep of this group returned to estrus repeatedly and did not get pregnant during the mating period, suggesting embryonic loss. It is concluded that M. tenuiflora cause malformations, embryonic mortality and abortion in sheep. In the third chapter, the paper relates a case of lissencephaly and cerebellar hypoplasia in a goat. The goat presented sternal recumbence, absent menace response, intention tremors, ataxia, and nystagmus. It was euthanized and necropsied after been hospitalized during eleven days. At necropsy, the surface of the brain was smooth, cerebral sulci and gyri were absent, and the cerebellum was reduced in size. Histologically, in all cerebral cortex, the grey matter was thicker and the white matter was thinner than normal. The neurons were arranged randomly in the grey matter. In the cerebellum, the layers were disorganized and there was heterotopy of the cells. The histologic and gross lesions are characteristic of lissencephaly associated with cerebellar hypoplasia. Lissencephaly is a rare disease in veterinary medicine and had not been reported previously in goats.